I know someone has had to deal with this. PLEASE HELP

My passenger door did this on one of my B Bodies years ago.I had to take out the front bench seat and then take of the interior door panel.Then I could lay on the floor and look up inside the door to see what was wrong.One of the little rods up inside the dorr fell off.I don't remember with one but I put it back on and the door could be opened from the inside as well as the outside.
I have also bought a car or two that had sat for a long time.Usally I could put my shoulder into it a bit to get it open.When I finally got it open I would spray the hell out of everything with PB Blaster.
Good luck,Jim