1993 Ford Bronco wont shift out of four wheel drive

Ok heres a little history, truck was running great but the check engine light is on, well it snowed alot so for the first time since I owned the truck I put it in neutral and shifted into 4h, now I diddnt go over 30-35 and only drove from where I engaged it to my home 4 miles away, at that point I parked it, put it in neutral and shifted the auto tranny to neutral, the four wheel drive to neutral, everything as far as I know seems fine up to here. I went to put it into park from neutral and I felt and heard a grind so I stopped quickly and put it back into neutral went through the entire range of 4x4 2h, 4h, neutral, then low, back to neutral, then it diddnt grind when I shifted into park, but to double check everything was ok I shifted into drive and it is if I was in neutral in all gears, so im stuck in four wheel drive. Any comments or suggestions on what my problem might be will be greatly appreciated.