After restoring SharePoint farm backup ( 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 connection)

Hi,

I have taken farm back and restore it in new UAT environment, while access to the main site getting the below error: 

Error  
An unexpected error has occurred. 

Troubleshoot issues with Microsoft SharePoint Foundation. 

Correlation ID: 866476f3-23dd-4e1e-97af-bffc62cc2d57 

Date and Time: 7/15/2014 11:26:35 AM 

When i checked in log i got below error

System.Data.SqlClient.SqlException: 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)    at System.Data.SqlClient.SqlInternalConnection.OnError(SqlException exception, Boolean breakConnection)     at System.Data.SqlClient.TdsParser.ThrowExceptionAndWarning(TdsParserStateObject stateObj)     at System.Data.SqlClient.TdsParser.Connect(ServerInfo serverInfo, SqlInternalConnectionTds connHandler, Boolean ignoreSniOpenTimeout, Int64 timerExpire, Boolean encrypt, Boolean trustServerCert, Boolean integratedSecu... 

Thanks in advance

Said Al Balushi