Just had this happen to me in my '05 Wangler Unlimited w/Auto Trans. Fellow Jeepster saved me $$ by doing the following:
From the cockpit, take the shift "T" handle off. To do this, put key in ignition; shift transmission into neutral. Push shift button in as far as possible (hard), then simultaneously pull with all your might. T-handle should come off. Don't worry, if you pull straight up, you won't brake it.
There will be a small plastic object inside the shifter shaft. Pull it up. Mine was about 3.5" - 4" long. (My buddy's was same length, so guessing yours will be same.) Looks like it has lobes on it. This "thingy" has broken at the bottom. Take this and cut a small diameter wooden dowel to match length-my dowel diameter was 3/16" I think. While you are at it, make 2 - one for spare. Keep in glove box.
Drop the cut dowel down the shifter shaft. Replace T-handle. Poof, should work. Let me know...