Do a search for 'Shifter Sheet'...it is most likely your problem.
To get it out of gear, pull your shifter off the T-Case from inside the truck, and there will be two rods that the shifter slides into. These two rods should make a 'square' that the shifter sits in. If this square is out of line, it wont shift. Line those two rods up with a screwdriver and it will work. Then, buy a new shifter sheet ($8-16), and install it.
You'll be Good to go.
This is an extremely common problem, and I wrote an extremely vague 'how-to'. Do a search, and there are pictorials on how to fix it. It is easy, takes 5-10mins total.
SQ