2001 Impala transmission lever stuck

I have 01 impala, base model, 3.4L SFI engine. I was driving one night and I ran into some water with my car. It was probably 10 inches deep. Next morning I started my car, went to shift in reverse and it was hard to shift. Same when I tried shifting in drive. I didn;t think much of it. Got to my destination, put it in park (hard again) and turned it off. Couple hours later I turned the car on, no problem, but it wouldn't shift at all. I managed to shift it moving the gear lever into drive with huge ranch. I put a brand new shifter cable in it, still wouldn't shift... so it's not the cable. The gear lever that is on transmission is almost completely stuck. Can't figure out why. I need your help.