Restore from last good backup, that's irrepairable.
If there's absolutely no backup whatsoever, export all the documents, lists, etc from sharepoint (not a SQL data export), then drop and recreate the sharepoint site. You'll probably lose some stuff.
Gail Shaw
Microsoft Certified Master: SQL Server, MVP, M.Sc (Comp Sci)
SQL In The Wild: Discussions on DB performance with occasional diversions into recoverability