4 WD, ABS, Brake & Speedometer

I have a 2002 Silverado 2500 4 X 4. Today, it got stuck in 4 wd. It is the push button type to engage/disengage 4 wd. The "Service 4 Wheel Drive" light came on, the ABS light and the "Brake" light also came on and the speedometer is not working. I can't get it out of 4 wd. I tried putting it in 4 low, and backing up to try and get it out? Any ideas what the problem could be and if it is serious/expensive to fix? Of course, the warranty ran out 4 months ago! Thanks