Do the parking/running lights work? Starting with the easiest, I would use a voltmeter to make sure the bulb is good (use the continuity setting), then see if there is power getting to the wire using a volt meter. It's possible a wire got pinched, has a bad connection, or got severed somewhere between point A and B. Good luck!
Try the easiest first....try cleaning out the dock connector with some canned air to see if there's anything keeping a good connection from being made. If that doesn't work, open it up and see if anything has come loose/broken etc.