One of two things will make a vehicle's gear selector stick in park:
- Brake pedal interlock circuit problem or brake pedal interlock solenoid failure; or
- Problem with the transmission linkage.
FIRST THING TO CHECK: ARE YOUR BRAKE LIGHTS COMING ON WHEN YOU PRESS THE BRAKE PEDAL? If not, your brake light circuit is having an issue, which means that the gear selector interlock solenoid will not release the gear selector. Check the fuse, the brake light switch under the dashboard, and all connectors. If your brake lights are coming on skip that.
SECOND THING TO CHECK: Have you tried manually releasing the interlock override at the gear selector? Check your user manual. It will instruct you to place your key in the slot near the PRNDL indicator on your center console (assuming that your gear selector is not on the steering column), or where to release the selector manually if the selector is on the steering column.
ARE YOU PARKED ON A HILL? Sometimes, parking on a steep incline will cause the park pin to jam into place. If this occurs, you will need to push the vehicle uphill slightly (get a couple of friends to help) so that you may get the vehicle out of Park.
IF you cannot manually release the gear selector using the override, you will need to have your car towed to a garage and have them check the transmission linkage. Sometimes the linkage gets jammed, sometimes the park pin gets jammed, and sometimes magical trolls interfere with our lives covertly... best of luck to you!