Most likely you are going to need a new shifter. It's not too common of a problem, but common enough. The Brake Transmission Shift Interlock (BTSI or Bitsy as we call it) Solenoid probably crapped out. The BTSI sends a signal to the ignition lock solenoid and tells it that it's ok to release the key. Ignition lock prevents you from taking the key out unless the car is in Park. The button on the bottom of the steering column is the fail-safe for when the BTSI quits. Its a small part, but you cannot get it separate of the whole shifter assembly.