error: 40 - Could not open a connection to SQL Server [duplicate]

Answer 1

I had the same problem and for some reason I had to add the standard SQL port (1433) and then everything worked again. In your case that would be:

string connectionString = @"Data Source=SYAZANA,1433;Initial Catalog=WangSCM;integrated security=true;"

Answer 2

Follow the steps:

*Go to SQL Server Configuration manager

*SQL Server Network Configuration:

*Protocol for MSSQLSERVER

*In the right pane split page you will have to disable VIA as follows

--->Shared Memory - Enable

--->Named Pipes - Enable

--->TCP/IP - Enable

--->VIA - Disable

Or Try the following

Go to Start -> in search type Services.msc. There you will find services which are available in your system.

There look for -> SQL EXPRESS / SQL Server (SQLEXPRESS) -> Right click on it -> then Start it . If it is already in Start. Just Stop and start or simply Restart it.