Pop the top of the shift lever off (pulls straight up) and check to see if the clip on the button is intact. From time to time they come off and do not lift the rod in the handle making shifting impossible.
If that doesn't work and the clip is still attached then then check to see if you have working brake lights. If your brake lights are not working then check fuse F1 in the fascia fuse box. Should solve your problem. Quirky isn't it?