RTC Connection Error

I had Nav 2009 R2 installed on my machine.

I am getting following error when i am trying to open RTC :

Microsoft Dynamics NAV

The Microsoft Dynamics NAV Server cannot connect the Change Listener to SQL Server because of the following error: 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)

Please suggest me the solution