Internal Server 500

I was trying to upgrade my wordpress to the latest version 3.1.3 from an earlier version. It appeared to hang so I clicked F5 to refresh the browser (IE) and it appear that it did not update. I now cannot either view my website http://www.vanns.co.uk or login to the dashboard
The error reads:
“
Internal Server Error
The server encountered an internal error or misconfiguration and was unable to complete your request.

Please contact the server administrator, [email protected] and inform them of the time the error occurred, and anything you might have done that may have caused the error.

More information about this error may be available in the server error log.

Apache/2 Server at http://www.vanns.co.uk Port 80
“
Does anyone have any clue how to resolve this.