Database Was in Suspect Mode, Now Detached, Can't Recover

Steps for Recovering Detached Database to Suspected State 

1. Create a DB with Same Name as the Lost DB.
2. Stop SQL Server Service.
3. Replace the .mdf & .ldf files with Old Files(Lost DB).
4. Start SQL Server Service.

Query For Recovering Suspected Database to ONLINE State 

EXEC sp_resetstatus 'yourDBname';

ALTER DATABASE 'yourDBname' SET EMERGENCY

DBCC checkdb('yourDBname')

ALTER DATABASE yourDBname SET SINGLE_USER WITH ROLLBACK IMMEDIATE

DBCC CheckDB ('yourDBname', REPAIR_ALLOW_DATA_LOSS)

ALTER DATABASE yourDBname SET MULTI_USER