stripped front sprocket nut
 

so i was putting the front sproket nut on and all is smooth until i go to give it the final tightening, and then nothing, the nut starts spinnig freely, i was confused at first and then i got the nut off and saw it had no threads, the nut is completely smooth where there used to be threads and the crank shaft's threads are pretty mangled. i'm hoping to re cut the threads on the crank with a dye but if it dosn't work i'll be screwd. has this ever happened to anyone else, what did you do to fix it, let me know.
thanks, -jonathan