Redirect to other page by dropdown list :

<?php

if (isset($_POST['nav'])) {

header("Location: $_POST[nav]");

}

?>

<script type="text/javascript">

$(function() {

    $("#submit").hide();

    $("#page-changer select").change(function() {

        window.location = $("#page-changer select option:selected").val();

    })

});

</script>

<h1 align="center"><strong>Search PAID Students Records</strong></h1>

<p align="center">&nbsp;</p>

<form name="form1" id="page-changer" action="" method="post">

    <div align="center"><strong>Select Your Option  &nbsp;&nbsp;&nbsp;&nbsp;</strong>

      <select name="nav">

  <option value="">Select Your Option...</option>

  <option value="paidstp.php">All Paid Students</option>

  <option value="paidlocation.php">Search Date & Location Wise</option>

</select>

      <input type="submit" value="Go" id="submit" />

    </div>

</form>