This may sound like a stupid answer, but mine did the exact same thing and I just drowned it in WD-40 and it started working again.

 

The rear drivers door sticks on mine often. Find the biggest wrench you can fit in there and pry up on the door while pulling on it. Once you get it open like cowboy bob said soak it in WD40 works for a while after that. just spray it once a week