@Music; şu şekilde deneyebilir misin?

<?php
	
	include "config.php";
	include "functions.php";
	
	function is_session_started()
	{
		if(php_sapi_name() !== "cli")
		{
			if(version_compare(phpversion(), '5.4.0', '>='))
			{
				return session_status() === PHP_SESSION_ACTIVE;
			}
			else
			{
				return session_id() !== '';
			}
		}
		else
		{
			return false;
		}
	}

	if(is_session_started() === false)
	{
		session_start();
		
		if(is_session_started() === false)
		{
			exit("Hata: Oturum başlatılamadı.");
		}
	}
	
?><!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Strict//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-strict.dtd">
<html xmlns="http://www.w3.org/1999/xhtml">
<head>
  <title>Gedik Üniversitesi Ödev Takip Sistemi</title>
  <meta name="robots" content="index, follow" />
  <meta http-equiv="Content-Type" content="text/html; charset=utf-8" />
  <meta name="author" content="RapidxHTML" />
  <link href="css/style.css" rel="stylesheet" type="text/css" />
  <script type="text/javascript" src="js/jquery.js"></script>
  <script type="text/javascript" src="js/jquery.easing.1.3.js"></script>
  <script type="text/javascript" src="js/fancybox/jquery.fancybox-1.3.1.js"></script>
  <link rel="stylesheet" type="text/css" href="js/fancybox/jquery.fancybox-1.3.1.css" media="screen" />
  <script type="text/javascript" src="js/easyslider.js"></script>
  <script type="text/javascript" src="js/custom.js"></script>
</head>
<body>

<!-- wrapper -->
<div class="rapidxwpr">

  <!-- header -->
  <div id="header">
  
    <!-- logo -->
    <div class="logo">
      <h1><a href="index.php">Gedik Üni.</a></h1>
      <span class="tagline">Ödev - Proje Takip Sistemi</span>
    </div>
    <!-- / logo -->
  
  </div>
  <!-- / header -->
  <?php if(!isset($_SESSION['oturum'])) { ?>
  <!-- mainmenu -->
  <div id="mainmenu">
    <ul id="menu">
      <li class="home"><a href="#tab1">AnaSayfa</a></li>
      <li class="portfolio"><a href="#tab2">S. S. S.</a></li>
      <li class="contact"><a href="#tab3">İletişim</a></li>
    </ul>
  </div>
  <!-- / mainmenu -->
  
  <!-- main body -->
  <div id="middle">
    <div class="middle_bg">

      <div class="tab_container">
      
        <div id="tab1" class="tab_content">
          <!-- page title -->
          <div class="page_title">
            <img class="profile_image" src="images/logo.png" alt="Profile Image" />
            <div class="contact_form">
                    <ul>
                    <form action="" id="contactForm" method="post">
            <li><label for="contactName">Ogr No</label>Öğrenci Numaranız :<input name="loginogr" id="logintc" class="input_item requiredField" type="text" /></li>
            <li><label for="contactName">Sifre</label>Şifreniz :<input name="loginsifre" id="loginsifre" class="input_item requiredField" type="password" /></li>
            <li><input type="submit" name="giris" id="submit" value="giris" class="submit" /></li>
                    </form>
                    <?php 
						if($_POST["giris"]) {
							$ogrno=$_POST['loginogr'];
							$sifre=$_POST['loginsifre'];
							
							$query = mysql_query("SELECT * FROM ogrenci WHERE ogrno='$ogrno' and sifre='$sifre'") or die (mysql_error());
							
							$say = mysql_num_rows($query);
							$cek = mysql_fetch_array($query);
							
							if($say > 0 ) {
								$_SESSION['oturum'] = true;
								$_SESSION['user'] = $ogrno;
								$_SESSION['pass'] = $sifre;
								
								header("refresh:0;");
							} else {
								echo "giriş başarısız";
							}
						}
                    ?>
                    </ul>
            </div>
            <br><br><br><br><br><br><br>
          </div> 
          <!-- / page title -->
          
          <!-- services -->
          <div class="services">
            <h2>Duyurular</h2>
            <?php 
            $result = mysql_query($duyurusql) or die(mysql_error());
            ?>
            <ul>
            <?php
            while($row = mysql_fetch_array($result)){
             echo "<li><font color='purple'>";
             echo $row['baslik'];
             echo "</font></li>";
             echo "<li>";
             echo $row['tarih'];
             echo " Tarihinde yazıldı</li>";
             echo $row['icerik'];
             echo "<br><br>";
              }
              ?>
            </ul>
          </div>
          <!-- / services -->
        </div>    
      
        <div id="tab2" class="tab_content">
          <!-- page title -->
          <div class="page_title">
            <h2>PORTFOLIO</h2>
            Mauris vulputate metus eu nisl. Praesent placerat. Mauris vitae erat id ante viverra sodales. Proin tincidunt porta velit. Praesent placerat. Mauris vitae 
          </div>
          <!-- / page title -->
      
          <!-- portfolio -->
          <div class="portfolio">
            <div id="slider">
              <ul>
                <li>
                  naber
                </li>
                <li>
                  iyim
                </li>
                <li>
                  senden
                </li>
              </ul>
            </div>
          </div>
          <!-- / portfolio -->
        </div>    
      
        <div id="tab3" class="tab_content">
          <!-- page title -->
          <div class="page_title">
            <h2>İletişim</h2>
            Gedik Üniversitesi Ödev / Proje takip sistemi hakkında isteklerinizi, hata bildirimlerini ve sorunlarınızı bize bildiriniz. Teşekkürler. 
          </div>
          <!-- / page title -->
      
          <!-- contact -->
          <div class="contact">
          
            <!-- contact form -->
            <div class="contact_form">
              <form action="" id="contactForm" method="post">
                <ul>
                  <li><label for="contactName">Name</label><input name="iletisimadi" id="iletisimad" value="Name" class="input_item requiredField" type="text" onclick="if(this.value=='Name')this.value='';" onblur="if(this.value=='')this.value='Name';" /></li>
                  <li><label for="contactEmail">Email</label><input name="iletisimmail" id="iletisimmail" value="Email" class="input_item requiredField email" type="text" onclick="if(this.value=='Email')this.value='';" onblur="if(this.value=='')this.value='Email';" /></li>
                  <li class="message"><label for="contactMessage">Mesajınız</label><textarea rows="5" cols="10" name="iletisimmesaj" id="iletisimmesaj" class="requiredField">Mesajınız</textarea></li>
                  <li><span class="required">Tüm Alanları Doldurunuz.</span> <input type="submit" name="submit" id="submit" value="Gönder" class="submit" /></li>
                </ul>
              </form>
            </div>
            <!-- / contact form -->
            
            <!-- get in touch -->
            <div class="get_in_touch">
              <h4>Buralardan Ulaşabilirsiniz.</h4>
              <ul>
                <li class="home">Lorem Ipsum Street, no.12 12062 Yogyakarta Indonesia</li>
                <li class="phone">(021) 123 456 789</li>
                <li class="email"><a href="mailto:email@yourdomain.com">email@yourdomain.com</a></li>
                <li class="twitter"><a href="http://twitter.com/instantshift">instantshift</a></li>
                <li class="facebook"><a href="http://twitter.com/instantshift">instantshift</a></li>
              </ul>
            </div>
            <!-- / get in touch -->
          
          </div>
          <!-- / contact -->
        </div>    
      
      </div>
      <span class="availability">available</span>
    </div>
  </div>
  <!-- / main body -->
  
  <!-- footer -->
  <div id="footer">
    Copyright &copy; 2014 Reşit Coşkun<br />
    <small>Designed by <a href="http://gedikuni.com/">Reşit Coşkun</a> and developed by <a href="http://gedikuni.com/">Reşit Coşkun</a> Tüm Hakları  <a href="http://gedikuni.com/">Saklıdır.</a></small>.
  </div>
  <!-- / footer -->

</div>
<!-- / wrapper -->

</body>
</html>   
      
<?php } else { ?>
<!-- mainmenu -->
  <div id="mainmenu">
    <ul id="menu">
      <li class="home"><a href="#tab1">AnaSayfa</a></li>
      <li class="portfolio"><a href="#tab2">Ödev</a></li>
      <li class="contact"><a href="#tab3">İletişim</a></li>
    </ul>
  </div>
  <!-- / mainmenu -->
  
  <!-- main body -->
  <div id="middle">
    <div class="middle_bg">

      <div class="tab_container">
      
        <div id="tab1" class="tab_content">
          <!-- page title -->
          <div class="page_title">
          <h2>Merhaba</h2>
            <img class="profile_image" src="images/logo.png" alt="Profile Image" />
            <div class="contact_form">
                    <ul>
            <li><label for="contactName">Tc No</label><input name="contactName" id="contactName" value="Tc No" class="input_item requiredField" type="text" onclick="if(this.value=='Tc No')this.value='';" onblur="if(this.value=='')this.value='Tc No';" /></li>
            <li><label for="contactName">Sifre</label><input name="contactName" id="contactName" value="Sifre" class="input_item requiredField" type="text" onclick="if(this.value=='Sifre')this.value='';" onblur="if(this.value=='')this.value='Sifre';" /></li>
            <li><input type="submit" name="submit" id="submit" value="Giriş" class="submit" /></li>
            
                    </ul>
            </div>
            <br><br><br><br><br>
          </div> 
          <!-- / page title -->
          
          <!-- services -->
          <div class="services">
            <h2>Duyurular</h2>
            <?php 
            $result = mysql_query($duyurusql) or die(mysql_error());
            ?>
            <ul>
            <?php
            while($row = mysql_fetch_array($result)){
             echo "<li><font color='purple'>";
             echo $row['baslik'];
             echo "</font></li>";
             echo "<li>";
             echo $row['tarih'];
             echo " Tarihinde yazıldı</li>";
             echo $row['icerik'];
             echo "<br><br>";
              }
              ?>
            </ul>
          </div>
          <!-- / services -->
        </div>    
      
        <div id="tab2" class="tab_content">
          <!-- page title -->
          <div class="page_title">
            <h2>PORTFOLIO</h2>
            Mauris vulputate metus eu nisl. Praesent placerat. Mauris vitae erat id ante viverra sodales. Proin tincidunt porta velit. Praesent placerat. Mauris vitae 
          </div>
          <!-- / page title -->
      
          <!-- portfolio -->
          <div class="portfolio">
            <div id="slider">
              <ul>
                <li>
                  naber
                </li>
                <li>
                  iyim
                </li>
                <li>
                  senden
                </li>
              </ul>
            </div>
          </div>
          <!-- / portfolio -->
        </div>    
      
        <div id="tab3" class="tab_content">
          <!-- page title -->
          <div class="page_title">
            <h2>İletişim</h2>
            Gedik Üniversitesi Ödev / Proje takip sistemi hakkında isteklerinizi, hata bildirimlerini ve sorunlarınızı bize bildiriniz. Teşekkürler. 
          </div>
          <!-- / page title -->
      
          <!-- contact -->
          <div class="contact">
          
            <!-- contact form -->
            <div class="contact_form">
              <form action="" id="contactForm" method="post">
                <ul>
                  <li><label for="contactName">Name</label><input name="contactName" id="contactName" value="Name" class="input_item requiredField" type="text" onclick="if(this.value=='Name')this.value='';" onblur="if(this.value=='')this.value='Name';" /></li>
                  <li><label for="contactEmail">Email</label><input name="contactEmail" id="contactEmail" value="Email" class="input_item requiredField email" type="text" onclick="if(this.value=='Email')this.value='';" onblur="if(this.value=='')this.value='Email';" /></li>
                  <li class="message"><label for="contactMessage">Mesajınız</label><textarea rows="5" cols="10" name="contactMessage" id="contactMessage" class="requiredField">Mesajınız</textarea></li>
                  <li><span class="required">Tüm Alanları Doldurunuz.</span> <input type="submit" name="submit" id="submit" value="Gönder" class="submit" /></li>
                </ul>
              </form>
            </div>
            <!-- / contact form -->
            
            <!-- get in touch -->
            <div class="get_in_touch">
              <h4>Buralardan Ulaşabilirsiniz.</h4>
              <ul>
                <li class="home">Lorem Ipsum Street, no.12 12062 Yogyakarta Indonesia</li>
                <li class="phone">(021) 123 456 789</li>
                <li class="email"><a href="mailto:email@yourdomain.com">email@yourdomain.com</a></li>
                <li class="twitter"><a href="http://twitter.com/instantshift">instantshift</a></li>
                <li class="facebook"><a href="http://twitter.com/instantshift">instantshift</a></li>
              </ul>
            </div>
            <!-- / get in touch -->
          
          </div>
          <!-- / contact -->
        </div>    
      
      </div>
      <span class="availability">available</span>
    </div>
  </div>
  <!-- / main body -->
  
  <!-- footer -->
  <div id="footer">
    Copyright &copy; 2014 Reşit Coşkun<br />
    <small>Designed by <a href="http://gedikuni.com/">Reşit Coşkun</a> and developed by <a href="http://gedikuni.com/">Reşit Coşkun</a> Tüm Hakları  <a href="http://gedikuni.com/">Saklıdır.</a></small>.
  </div>
  <!-- / footer -->

</div>
<!-- / wrapper -->

</body>
</html>
<?php } ?>