Hard to understand your question, I made 2 possible parts: Part 1 you have only front wheel drive and no rear wheel drive. Part 2 your rear wheels locked and they doesn't allow the truck to move.
If the first part, what did you select for 4wd, Auto, 4 hi or 4 low? Maybe your transfer case or the selector mechanism is not right.
If the second part, maybe your parking brake is stuck on?
Sounds like your brakes are locked up on the rear axle or you grenaded your read differential. Or just let it run out of gear lube if you don't have a powerful motor in it.
Locked up muffler bearings...
I have a Chevy Silverado that is not a newer version but a little old kind of version. The wheels are locked up and if you put it into drive, they go nowhere. But if you drive it, the front wheels will pull the back wheels across the field. At the time, it was sitting in the middle of a grass/stone when it happened, so I just hooked it up to my 2012 Chevy Silverado 4x4 and drug the ****** across the grass and parked it somewhere else. Why are the rear wheels locked up and what are things I can do to make them move again?