Can anyone help me?

My 04 Silverado is stuck in 4 wheel lo.  I went through a low river and it will not get out of 4 wheel lo.

The shift switch lights are all working.  Backing up won't help.  When I try to put it into 2wd or 4wheel high or auto, the lights flash but won't stay on.  The transfer case shift motor sounds like it is engaging or trying to.

What else can I check?

Thanks