WPMU Wildcard Sub-Domains Lost

I have had some technical issues on the server side of the main site I am using your themes and plugins on. The server had to be restored after a security issue and everything seemed to come back ok except all the subdomains (user blogs) do not show correctly any more and go to the default apache page. The domain wildcard dns record is still in place. So I guess my real question is, is there a file somewhere that can be reconstructed to reflect all the existing blogs on the main domain?