Web server unable to connect to SQL Server

I have a site working under IIS7 and it was working fine. Someone restarted the server and after that it stopped working. After searching about the issue I found it is unable to connect to SQL Server and here is the 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开发者_运维知识库 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)

I didn't do any changes and the site was working fine but this problem happened only after restart, I checked SQL server remote access and TCP protocol and they were enabled. How do I fix the issue?

• Check connection strings (shouldn't be this if you didn't touch it)
• Check that the SQL services are up and running
• Try connect to the SQL server instance via Management Studio or another client

EDIT:

The error may be due to a network issue relating to the reboot. Try these out

Part 1: http://blogs.msdn.com/b/sql_protocols/archive/2005/10/22/483684.aspx

Part 2: http://blogs.msdn.com/b/sql_protocols/archive/2005/10/29/486861.aspx