BMW Repair: Transmission, solenoid pack, shift linkage

Question
I was driving up hill one day and my friend switched my car into nutral then i switched it back to first as fast as i could but when i was going back down the hill it was stuck in first and when i stopped none of my forward gears worked it only works in reverce now do i need a new transmissin or only a part? and do you know at all how much this might cost me? It's a 1985 735i  

Answer
you could have done a few things such as bent the shift linkage or a solenoid problem caused by the lever being manhandled back into 1st.  The fact that it only goes into reverse means the linkage isn't pushing a rod far enough to get into gear or the solenoid pack is clogged/has a fault.  you'd be best off having a trannie shop take a look at it.
-cheers