Microsoft SQL Server Error 2: Can not connect to the. server instance

The video handles the following error message of MS SQL Server:
Cannot connect to …
Additional Information
A network-related or instance-specific error occurred while establishing a connection to SQL Server. The Server was not found or was not accessible. Verfiy that the instance name is correct and that SQL Server is configured to allow remote connections. (Provider: Named Pipes Provider, error: 40 – Could not open a connection to SQL Server ) Microsoft SQL Server, Error: 2).
The system cannot find the file specified.