You need to remove the suspect mode from the server first then you can attach the database.

Run the following queries to remove the suspect mode:

EXEC sp_resetstatus ‘yourDatabasename’;

ALTER DATABASE yourDatabasename SET EMERGENCY

DBCC checkdb(’yourDatabasename’)

ALTER DATABASE yourDatabasename SET SINGLE_USER WITH ROLLBACK IMMEDIATE

DBCC CheckDB (’yourDatabasename’, REPAIR_ALLOW_DATA_LOSS)

ALTER DATABASE yourDatabasename SET MULTI_USER

Note: You might choose some amount of data.