I installed sharePoint 2013 successfully. But after everything being installed for no reason I changed my servername! After that nothing seems to work properly.
So I renamed it back but When I reran the Sharepoint product configuration, it failed with this message:
An exception of type System.IO.FileNotFoundException wan thrown. Additional exception information: could not file C:\inetpub\wwwroot\wss\VirtualDirectories\17168\web.config