How to solve a login problem of SQL Server?

Sometimes when we attempting to login the SQL Server 20xx Management Studio, when we type in the correct password, it fail S with:

"a network-related or instance-specific error occured while establishing a connection to SQL Sercer. The server was not found or is not accessible. Verify The instance name is correct and that SQL Server is configured to allow remote connections. (Provider:sql Network Interface, error:26-error locating Server/interface Specified) (. Net SqlClient Data Provider)"

There is possible ways to solve it:

1) A-by-cmd command:

Step 1:run cmd (as Administrator);

Step 2:type in "net start mssqlserver" and press Enter;

Step 3:enjoy SQL Server now.

2) A-to-mouse click:

Step 1:right Click at the ' thiscomputer' icon on your desktop or at the ' thiscomputer' tag on the Lef T in any Explorer window;

Step 2:choose the "Manage" menu;

Step 3:double Click the "Service" on the function tree;

Step 4:find "MSSQLSERVER (SQL Server (MSSQLSERVER))" and right click at it;

Step 5:choose start;

Bingo!

Sometimes, the "SQL Server (MSSQLSERVER)" Service won't run properly, just start or restart it may solve many problems.

-This was a note I wrote on the 10th, 2015. Many syntax mistakes may occur in the passage, but this is a milestone to me. Keep going!

How to solve a login problem of SQL Server?