Cannot detach a suspect or recovery pending database. It must be repaired or dropped.

Note: Below method of removing database is only when database shows RECOVERY_PENDING because of  MDF/LDF files missing.

Solution:

ALTER DATABASE DBNAME SET OFFLINE
GO
sp_detach_db 'DBNAME'
GO


In Other Cases Please Refer to (Please Note: Check with customer for dataloss)

https://dbamohsin.wordpress.com/2012/01 /23/cannot-detach-a-suspect-or-recovery-pending-database/

Prefer: Use latest backups available to restore the database.