Your shifter may be stuck in the park position, because of the brake release that is on the inside of the shift lever. You can remove the shifter cover to access this, and simply release, or replace the plastic device that can break, causing you not to be able to press in the button. This is referred to a shift lock selinoid, and can be purchased at a salvage yard or local auto parts store.
〉 Answered on Jul 30th, 2013 by Amanda J. Pierce, MBA "AJ", Certified Mechanic, Project Coordinator; Primavera Scheduler at VIGOR Alaska Industrial Shipyard & BizzM3ch Solutions
First check automatic transmission level. If it hasn't even serviced in a long time you should have the transmission fluid changed.
〉 Answered on Jul 30th, 2013 by Barb Petrey, President - DBK Enterprises Inc at Jiffy Lube