What can I do when lock, wheel, and ignition are frozen?

Try this, put the key in the ignition while trying to turn the key move the steering wheel back in forth (right to left) as much as you can. Sometimes the steering wheel lock will hang up. Seems to be a common problem on older mb vehicles. The door lock problem will be the plastic tab lock on the backside of the lock tumbler. It will require removal of door panel, outside door handle and striker in some cases.