SQL Server 2008 R2 Stuck in Single User Mode
Try the below commands
First run these three commands
USE [master]
SET DEADLOCK_PRIORITY HIGH
exec sp_dboption MyDBName, 'single user', 'FALSE';
Second run these two commands
ALTER DATABASE MyDBName SET MULTI_USER WITH NO_WAIT
ALTER DATABASE MyDBName SET MULTI_USER WITH ROLLBACK IMMEDIATE
In first run following query in master database
exec sp_who
If you can't find the culprit, try
SELECT request_session_id FROM sys.dm_tran_locks
WHERE resource_database_id = DB_ID('YourDatabase')
Then kill all process that use your database with following query:
KILL spid
Then run following query:
USE Master
ALTER DATABASE YourDatabase SET MULTI_USER