2000 Other Chevrolet Models 4X4 front Axle will ot engage

I have the old classic type K2500 4x4. When shifted into 4x4 the front differntial will not engage. The Axle from the transfer case to the froint differnetial will turn but the tires do not. It all started when I went 4x4ing and got into a small creek that covered more than half of my tire. That day after and the whole drive home the 4x4 would not disengage even with the transfer case shifter in the 2 wheel postion. In time (2-3 weeks) it went back to normal 2 wheel drive, but now it wont engage. The light does turn on and agian the axle will rotate fromt he transfer case but it is not applying the power to the wheels. Its obvious the water or something damaged or hurt something. Any suggestions?