You will have a fuse gone. It is a red 10 amp fuse but I cant remember the fuse without looking so check them all. You should find that this fuse blows everytime you put it in reverse. This is because your reverse switch is broken and will cost you around £15.00 from main dealer. It is screwed into the top of the gearbox. Re post a question if you cant find it saying cant find reverse switch on gearbox.
Kind Regards.
Tristan Hanwell, September 2006