SQL Server 2008 R2 Stuck in Single User Mode

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

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

This was answered here, the code is:

use master
ALTER DATABASE YourDatabase SET SINGLE_USER WITH ROLLBACK IMMEDIATE 

--do you stuff here 

ALTER DATABASE YourDatabase SET MULTI_USER