how to repair suspect db
Its good to restore from an earlier backup copy.If you dont have one..below are the steps that can be done to repair suspect database..this has been explained with more examples by Paul Randal here :Creating, detaching, re-attaching, and fixing a SUSPECT database

Overview of steps


set suspect database offline  
Copy those mdf ldf files to some location  
drop the old suspect database  
create a new database with same name and same file layout  
set this new database offline
delete the newly created mdf,ldf files and copy old corrupted files
now try bringing the database online and try repairing with DBCC


below are the scripts

CREATE DATABASE DEMOSUSPECT

ALTER DATABASE DEMOSUSPECT SET OFFLINE

--- you have to copy and drop the old database files prior to this
----NOW DELETE THE mdf and ldf files created for new database

--copy those corrupted files into new location
alter database demosuspect set online

 --check status once
SELECT DATABASEPROPERTYEX (N'DemoSuspect', N'STATUS')

--tyr putting the database into emergency mode and use DBCC
ALTER DATABASE [DemoSuspect] SET EMERGENCY;
GO
ALTER DATABASE [DemoSuspect] SET SINGLE_USER;
GO
DBCC CHECKDB (N'DemoSuspect', REPAIR_ALLOW_DATA_LOSS) WITH NO_INFOMSGS, ALL_ERRORMSGS;
GO


-- Check the state
SELECT DATABASEPROPERTYEX (N'DemoSuspect', N'STATUS') AS N'Status';
GO