How to resolve this problem,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) (Microsoft SQL Server, Error: 2).The system cannot find the file specified

Hi,

Please refer to the following article to troubleshoot the issue:

How to Troubleshoot Connecting to the SQL Server Database Engine

Best regards,

You don't say where your SQL server is, so is it one the same machine you are accessing it from in which case the chief suspect is that the SQL Server service is not running (check in services). 

If Not then the previously mentioned troubleshooting guide will help, for example

and the top three are 1. Is the SQL Server service running on the target server? 2. can I ping the server where SQL Server and resolve it in DNS (if you are using a server name)? 3. Is the SQL Server port open on the server firewall (1433 by default)?

let us know how you get on and mark the best answer as an answer to help the next guy who has this problem

thanks @deepfat