2012 jeep grand cherokee overland 3.6 didn't engage 4wd low now wont do anything

I was trying to go through the terrain modes in my
jeep and it said I had to put it in 4 low for rock
mode so I hit the button and it flashed and came
on like everything was fine but when I tried to take
it out it wont do anything at all. It wont move in
drive or reverse when I try to change terrain out of
auto the snow mode blinks and goes back to auto
or it jumps to sport and does the same. When I
press the 4 low button it does nothing at all. What
should I do to get it going again? Or am I just in
store for an expensive mechanic bill?