Primeiro, você não precisa repeatinclude("guestlist_connect.php"); E também esqueceu de terminar o loop while
<?php
include("guestlist.php");
include("guestlist_connect.php");
?>
/*invites.HTML*/
<h2 >Invites & Guest List</h2>
<table border="2">
<thead>
<tr>
<th>First Name</th>
<th>Last Name</th>
<th>Contact</th>
<th>Invitation</th>
</tr>
</thead> <tbody>
<?php
$result = mysql_query("SELECT * FROM guestlist");
while( $row = mysql_fetch_assoc( $result ) ){ ?>
<tr>
<td><? php echo $row["fname"]; ?></td>
<td><? php echo $row["lname"]; ?></td>
<td><? php echo $row["email"]; ?></td>
<td><? php echo $row["contact"]; ?></td>
</tr>
<?php } ?> // you forgot to end a while loop
</tbody> </table>
<?php mysql_close($connector); ?>
</div><!--End Rightcontainer--> </div>
