Microsoft SQL Server , Error : 87

Question

I am really tired, it's been 3 days that I can't open my SQL Server Management Studio. I got connection string error with number 87. Below screenshot show my problem:

And I use localhost\MSSQLSERVER with error 87 and Arash-PC (my machine name) with error number 2.

And I tried sqlcmd -U sa -S Arash-PC too

Answer 1

You need to check in your SQL Server Configuration Manager what services and instances you have installed. Go to Start Menu > All Programs > Microsoft SQL Server (version) > Configuration Tools and launch the appropriate Configuration Manager. You should see a screen something like this:

Find the SQL Server (.....) service(s), and make sure the service is started.

If you find a SQL Server (MSSQLSERVER) service started, then you have a (unnamed) default instance to which you can connect using

.
(local)
Arash-PC

You MUST NOT supply the MSSQLSERVER as the instance name!

If you find any other SQL Server (instance name) service started (e.g. SQL Server (SQLEXPRESS) in my screenshot), then the instance name (SQLEXPRESS) needs to be appended to the server name to connect to that instance:

.\SQLEXPRESS
(local)\SQLEXPRESS
Arash-PC\SQLEXPRESS