99 Blazer transfer case stuck in neutral?

I have a 99 blazer 4x4 w/4.3 litre auto w/overdrive and electric shift for the 4x4 w/4button control in dash. I can shift the transmission and it seems to be shifting as I can feel it start to turn and when returning the lever to park the pin will grind into park if I don't shut the vehicle off. I have no forward or reverse no matter where I select the controller switch for the 4x4. In park I still have to block the wheels or it will roll downhill. I can press the buttons for the 4x4 and here nothing shifting, no lights come on at the buttons. Can anyone help, I see lots of posts with problems shifting from one range to another but still can drive it, I have no movement at all? No hard driving been done, working fine then backed up 15 feet and lost all functionallity. HELP. Mileage 180,000 km.