guestbook hacked

My guestbook has been hacked by Dubious Duo and the master. I can't get at my admin and I have no idea how to repair it. Can anyone help me please.

I have found that there is a file called config.inc.php which has the hacked message in it and it seems that the files in the guestbook directory are calling this page. I don't know what should be there and what shouldn't.

Is there a way of finding out which files have been tampered with and which are still originals.

Regards

harlequeen

What version of the guestbook was it?

Download the guestbook and replace every file except admin/config.inc.php