If the key rotates but does not move the rod, it could be a key lock tumbler problem inside the tumbler itself, or it could be that the linkage that connects the tumbler to the rod has failed or simply fallen off the tumbler's arm. I have seen the problem caused by either problem, but probably the better odds are the rod has become disconnected from the key arm. Can you see if the tumbler arm itself is actually moving when you turn the key?

Another thing I've seen before was the arm did not move enough to move the level in the latch assembly into the lock, or unlock position on the latch. that can be caused by either the plastic rod holder has failed or come off, or it could be the rod or the latch lock lever has been bent. Usually with this, you can see the outside tumbler arm move with the key, and you can see it move the rod.

The picture shows a door latch assembly out of a 92ish Dakota door. The paper behind the latch is kind of hard to read, but it tells what each plastic clip and its attached arm does on the latch assembly. With each clip, the rod that pulls or pushes on the lever slides into the hole on the clip and the plastic arm locks onto the rod and keeps the rod in the proper position to move the lever as far as it has to move to chance what that part of the latch does. picture that plastic as the steel clip that holds the choke rod onto the carb choke linkage, only in plastic and on the door latches, handles, and lock rods, on both ends of the rods. If the plastic fails on either end of the rod, the rod can't do its job. Gene