title: SQL server connection in Visual Studio stop working
body: <p>I was writing a programm, and I used SQL, and it was working just fine, but suddenly it can't connect to the server.
  This is the error I got:
  "A network-related or instance-specific error occured while
  establishing a connection to SQL Server. The server was not found
  or was not accessible. Verify that the instace name is correct and
  that SQL is configured to allow remote connections.
  (provider: SQL Network Interfaces, error: 26 - Error Locating
  Server/Instance Specified)"
  I am using Visual Studio 2010, and SQL server 2008.
  I can't figure out what the problem is and I'd appreciate anyone who helps.</p>