I Have a 95 Isuzu Rodeo. The only way it will move is when I drive it in 4 wheel drive. Is this the trans.?

It happened all in one day. I was driving and when I had to stop & start up again it would shake really bad. I drove about 20 more miles & by then my truck would not even move out of 1st gear. I can drive it in four wheel drive not very fast but I can. I was then told If it was the transmission I would not be able to drive it in 4 wheel drive either. If anyone has any ideas please fill me in. I called around and the cheapest I could get my transmission rebuilt was still over one thousand bucks. I just don't have that. If it could be anything other than the transmission & anybody has any guesses please let me know. Thanks