My Merrc Capri passenger door will not open!!~
If the mechanism is rusted, you can roll the window down and squirt penetrating oil on it. Work the handle to get the frozen parts moving. Look at the other door to see what parts are supposed to move.
If the parts are broken or the rods came apart like the Judge says, Look at the other door and try to move the similar parts in the stuck door with a long rod or lever. If that fails, follow the Judges instructions of panel removal.
Good luck. Join this group: https://www.facebook.com/groups/mercurycapri/ and ask for suggestions