Sorunu çözdüm belki lazım olan arkadaşlar olabilir.
<?php
$servername = "localhost";
$username = "root";
$password = "root";
$dbname = "urun";

// Create connection
$conn = new mysqli($servername, $username, $password, $dbname);
// Check connection
if ($conn->connect_error) {
die("Connection failed: " . $conn->connect_error);
}

$aranan = $_POST['barkod'];
$sql = "SELECT * FROM urun";
$result = $conn->query($sql);
$sayac = 0;
if ($result->num_rows > 0) {
// output data of each row
while($row = $result->fetch_assoc()) {
?>
<?php
$sayac++;
echo $sayac;
echo "<br></b>";
?>
<?php }
} else {
echo "KAYIT YOK";
}
$conn->close();
?>