<select name="lang" onchange="redirect(this.options[this.selectedIndex].value);">
  <option selected>DİL SEÇİNİZ</option>
  <option value="/?lang=tr">Türkçe</option>
  <option value="/?lang=en">English</option>
  <option value="/?lang=ar">العربية</option>
</select>

<script type="text/javascript">
var redirect = function(href){
  document.location.href = href;
}
</script>