ELECTRIC PROBLEM

Hi Anyone have any ideas on how to cure an electrical problem, My interior light, clock, radio, and hazard lights don't work, last week whist off roading I hit a big bump and every thing worked until the next big bump now all the above not working I've striped out the dash board and all looks fine, their is a green box behind the speedo which looks like an after market alarm( if I unplug it nothing works ) have checked all earth straps I can find all are good, and tested for power at all relavant points but no power, the problem is on a 1999 land rover Defender 110( EX EDF ENERGY VECHILE)

I suspect the bump may have been your battery falling out... or maybe the engine dropped out ?