I was driving my 91 GMC Jimmy after a snow storm in 4wd and it was working fine. Then later i started to hear a rubbing/ squeaking sound and didn't think much of it. Then later on that night I went to move my Jimmy and the 4wd didn't work at all. I don't know what to do. Its my only transportation to school and with my 4wd out its harder for me to get to school.