OK, first of all, welcome to the forum.
Can you give us a little history as in did this happen all at once?
How long have you had the bike?
Did it lock up while you were riding it?
Have you put it on the center stand and moved the rear wheel while trying to shift it?
Did you take the round cover off the engine on the left side and put a socket on the nut and try to move the crank?
If you put a socket and bar on the crank nut, when crank stops moving, is it sudden stop?
OK, here are a few things to think about and maybe we can help out a little better.
RandyA