I cannot turn my ignition off and the key wont come out in my 2002 gmc envoy

Try using the door key to lock and unlock the drivers door.

Sounds like a bad ignition lock cylinder.

Try system reboot. Disconnect engine battery for two minutes, reconnect and turn the ignition key to the 'on' position and wait two minutes for the system to recalibrate actuators.

a lock smith can change your ignition switch at the house usually

Replace your ignition switch, common problem, especially in 2002. As far as getting your key out:

Look under the switch that you put your key in on the bottom part of the steering column cover....In your year, some have an open hole there in which you can push the solenoid to release your key. Others have an outline of where a hole was going to go, will be very faint. But this can be carefully cut or drilled out to access the solenoid.

Try resetting the ECM, turn the ignition key to the on position "engine not running" and pull the fuse to the ECM and place it back in. Leave the keys in that position for 30 seconds and then turn it off and on again for 5 seconds and start. this will reset the ECM to default. It may stall again but let it, just start it again and let idle for 3min and go foe a test drive. This should reset the way the engine and transmission performance, and should reset the idle issue on your Envoy. Good luck and keep me posted.

check battery and replace if required.

This could be a bad key. Expensive but if necassary to replace to check on the symptom of the car since no codes are being thrown. I would also say check your Idle Air Control valve and your EGR valve to make sure they are working proplery

I can not release the key from the ignition. I have replaced the PNP switch. If I wait ten to twenty minutes it will release it sometimes. I don't know what to do from here. Please Help!!!!

If your 2002 gmc envoy or sierra will not even turn over with a kown good battery try starting it in nuetral then go back to park and try starting again. There is a park nuetral safety switch that can malfunction. Turn the key on then shift into nuetral, then turn fully to start.