first you need to "find" the problem. with the engine Off (not running) spin the spur gear by hand, will the car roll? if not check the reverse links. move it by hand with the radio off to see if it will engage. if all of this works then check the clutch. but you need to see if it is in the tranny or the clutch. I beleive it is next to impossible to mess up the FWD gears but i do beleive thier is a pin inside that could had busted if you were doing something very rough. is this a new out of the box truck or was it working and then quit? give the whole story and you will get better direction.......