buenas tengo este problema al abrir el mu marker me sale esto

A network-related or instance-specific error occurred while establishing a connection to SQL Server. The server was not found or was not accessible. Verify 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)

lo estas tratando de abrir locamente o remotamente ? si es localmente revisa bien si has puesto la contraseña del sql y si es remotamente revisa que estea abierto el port 1433