Rebuild last comments

Hi, I had some spammers today and had to delete all. The automatic function deleted all the posts made by this spammer but in the forum list the last comment is "deleted user" and the day is today. He spammed on many very old topics and now they are in the first page :-(
Is there a system for rebuild the last comments?
Thank you
You can see my problem here
http://www.mortalitalia.it/forum2/
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Comments
I knew this couldn't be a new problem! Did this and go that :-)
Thank you R_J. Sorry, but my english is sometimes is bad and I didn't know wich keywords search on google for the best result xD
No problem. I've searched for the SQL terms that were part of the solution and if you would have known the solution, you wouldn't have had to ask ;-D