Un-Stick a door latch

I ended up using several pry bars and plywood to protect the body when my dart latch stuck. Mind you, it was never opened for 20 years. The dog that goes over the striker bolt was seized in the latch housing. Almost cut a hole in the door. I did get trim panel off, but it still took hard prying to open it. Contrary to public belief,wd-40 isnt the worst squirrel piss out there.