you might be face this situation in past, you tried to connect the SQL Server but SQL Server is not responding. In this situation you can follows the below steps to connect SQL Server:-
- Connect using DAC via CMD or SSMS
- Connect via CMD
- SQLCMD -A –U myadminlogin –P mypassword -SMyServer –dmaster
- Once you connect to the master database run the diagnostic quires to find the problem
- Correct the issue and restart the server