First, check that the transmission drive belt has not snapped or jumped off the pulley(s). If the pulley on the top of the axle is rotating, and tractor is in gear and not moving, the tranaxle has failed.
This would be unusual, however - usually you only lose one or two gears. For reverse to fail as well, the differential would have to have failed, and it's pretty robust!
One other thing - check that the key in the wheel(s) hasen't sheared. If the axle can rotate in the hub, there's the problem!
phil_saunders(a)bigfoot.com
Phil Saunders, July 2009
