So I was driving my 96 xj (in 2wd) and I tried to do a U-turn. When I turned the wheel as sharp as it could go, something started popping underneath. Now my shifter is stuck to the very left and can only go in 1st and 2nd gear. Whenever I go forward, a popping action occurs to the front wheels. Also, when I try to engage 4wd, nothing happens. What did I do. How can I fix. New tranny? new t-case? any advice????

 

Off hand, I'd say you should crawl under the Jeep and examine the transmission mounts, linkages, etc. Also examine the engine mounts.

 

This is a manual transmission I take it?

I'm with Ken. Some mounts or bushings are toast and let something shift.