Script Senha

Código PHP:

<?php
include "banned.php";
include "banneduser.php";
include "checkcookie.php";
include "title.php";
include 'counter/counter.php';
?>
<div id="title">Editar senha:</div><p />
<form action="index.php?do=changepassword" method='post'>
<table align="center">
 <tr><td><b>Senha atual:</b></td><td><input type="password" name="oldpassword" /></td></tr>
 <tr><td><b>Nova senha:</b></td><td><input type="password" name="newpassword" /></td></tr>
 <tr><td><b>Repitir nova senha:</b></td><td><input type="password" name="repeatnewpassword" /></td></tr>
 <tr><td></td><td><input type="submit" name="changepassword" value="Editar senha" /></td></tr>
</table>
</form>
<?php
if ($_POST['changepassword']){