Before you get to far ahead here and start to tear things apart try wiggling the steering wheel back and forth while you work the shift lever the steering lock can affect the shift lever if its hard against the lock so moving the steering of the lock can release the shift lock.
If this doesn't work then you need to check the shift lever itself for issues and also the cable that runs from the shift lever. Fraying of the cable ends can cause the shift lever to bind and not work. To check both you'll need to remove the council around the shift lever .