Auto Gearshift Stuck in Park

I have a 2004 Nissan Sentra, 1.8L automatic transmission, with 90,000 miles on it. I just drove it to the store, When I came out of the store, I could not get the shifter to move out of the Park position. Of course, I already tried firmly depressing the break, and the car runs perfectly otherwise.

The steering wheel is not locked. But I do hear a 'clicking' sound near the ignition key, everytime I push the button (to shift) on the side of the shifter. The button will not totally depress. I need to know how to either bypass this mechanism or to fix it. Please help!