Please run the following and post the full and complete output.
DBCC CHECKDB (<Database Name>) WITH NO_INFOMSGS, ALL_ERRORMSGS
Depending how bad this is, it may be necessary to restore from backups. Do you have clean (uncorrupted) backups of this database. For some background info on what's happened take a look at this article. http://www.sqlservercentral.com/articles/65804/
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