Attached files missing

[alexchairman]

under maintanence,i went for repair/optimize tables.selected all the options and did repair.

after doing this process the following error is coming in the admin pannel
Database error in vBulletin 3.6.8:

Invalid SQL:

SELECT COUNT(*) AS count
FROM attachment AS attachment
INNER JOIN post AS post USING (postid)
WHERE attachment.visible = 0;

MySQL Error : Table './alexforum/attachment' is marked as crashed and last (automatic?) repair failed
Error Number : 144
Date : Saturday, November 10th 2007 @ 05:02:19 PM
Script : http://xxxxxmobiles.com/forums/admin...ex.php?do=home
Referrer : http://xxxxxmobiles.com/forums/admincp/index.php
IP Address : xxxxxxxx
Username : xxxxxx
Classname : vB_Database





and also in forum attached files are missing(not shown)

need help.plz reply