SQL Server 2014 does not connect

Question

I have been working on SQL server 2014. It was working fine. Today when i was trying to connect to server it is not connecting. It is showing this error.

Answer 1

This probably is the issue because Windows turn off some services to optimize the windows performance, You should Try this:

Search Services in your search bar and open it, Search for SQL Server Services from the list of services, right-click > start and try connecting to your SQL Server again. make sure they are running

Answer 2

如果要输入正确的数据库凭据，请从控制面板的“服务”选项卡中启动MSSQLSERVER服务

Answer 3

Probably you might want to start SQL server using SQL server configuration Manager (you can find it directly from Start menu) or you can go to the path in your C Drive based on SQL server version

See link from Microsoft: https://docs.microsoft.com/en-us/sql/relational-databases/sql-server-configuration-manager?view=sql-server-2017