05shee!

hey i am new to this sight... i have been riding a banshee for about 6 years now... i have been having some problems with the shee lately tho... so i need help... im sure i could figure it out by teareing it down but i just wanted to ask 1st to see wat i could come up with... i was riding up a steep hill climb and hit a medium rock on the way up and almost lost it but like your typical crazy guy on a banshee i kept goin full throttle balls out! then here comes the last part of the climb also the death of the shees transmision, i hit another big rock n poped up in the air and lost all momentum so i quickly shifted down from 4th to 1st and bang the engine died! so i fire it up again i only have like 20 more feet to the top so i hit the gas and dump the clutch the bike instantly stalls out like theres a big stick or rock stuck in the chain! so i get off the shee to figure out wat the problem is and come to the conclusion that there is no rock, or stick stuck in the chain!.. its 1st gear! 1st gear is solid! so i try seccond gear and it takes off like it should so i hit the gas and make it to the top... once on the top with the rest of the guys we look over the bike and sure enough 1st geaar is solid! si i ride the bike back to the cabbin without 1st... so wat might have broke?any input would be great