$an=mysql_query("SELECT id FROM tutabla WHERE id < $id ");
$row=mysql_fetch_array($an);
$ida=$row['id'];
$si=mysql_query("SELECT id FROM tutabla WHERE id > $id ");
$row=mysql_fetch_array($si);
$ids=$row['id'];
$prev = $ida;
$sig =$ids;
"SELECT min(id) as minimo, max(id) as maximo FROM tu tabla ";
if($id != $datos['minimo']) {?>
<a href="page.php?id=<?php echo $prev; ?></a>
<?php }else {
?>
<img src="img/block.png" alt="Primer id" />
<?php }
if($id != $datos['maximo']){?>
<a href="page.phpid=<?php echo $sig; ?></a>
<?php }else {
?>
<img src="img/block.png" alt="Último id" />
<?php }?>
ES MAS O MENOS LA IDEA, ADAPTALA .