One reason is that the cable that runs to the steering column could be jambing up the ignition. Some times it is possible to reach under the steering wheel and move the cable. Sometimes this frees the key. Another reason for a key getting stuck in the ignition is related to the shifting mechanism. If it gets locked, you can try moving shifter into park a little harder. Step hard on brake pedal. Rock the wheel back and forth while trying to get the key out.