Ok, have him do the following:
First, rock vehicle back and forth a few times. If the transmission position switch isnt locked into park it will prevent the key from turning. Doing this will ensure it is in park.
If no difference, have him disconnect the battery for 10 minutes and reconnect. This will reset the interlock solenoid if it is preventing it from starting.
If he is parked on a hill and wheels are turned and locked, have him jack up front end with rear wheels chocked to prevent it from rolling. With front wheels off the ground, this will unlock the steering wheel to turn the key.
If still no go, have him GENTLY tap around the ignition cylinder with a hammer as he turns the key. If the tumblers for the key are sticking, this will free them and allow the key to turn
If still no go after all this, then the ignition key cylinder tumblers are broken and will need the cylinder replaced and tumblers coded for his key.
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