[jamie 6.5t]

please help right i just took my car out onto the front on some grass and driving fine until i got it on the grass and then a bump came along and then lost drive to my wheels from the gear box the spur gear was still spining with my motors pinion so what have i done im guesing that when i jumped one of the sprockets in the gear box has shifted :/ is it an easy fix or will i have to take it to my local shop :/