The transmission will not engage

The transmission will not engage The truck has been working fine I pulled my boat out of the lake got it into my garage and it was in four wheel low once I got onto my property because I had to pull it to grass. Got it into my garage turn my truck off. Turn the truck back on and now the transmission won’t engage it still says four wheel low but I put it in neutral try to shift to 2 Wheel Dr. regardless when I put it in drive the engine revs but it does not engage