I've searched the forum, but no one seems to posted this exact problem before. I'm grateful for any guidance anyone can provide.
Issue:
2005 MDX with 190,000 miles.. suddenly the drivers side door keylock will not work. The key inserts smoothly, and turns both right and left, but does not lock or unlock the car. I've tried both spare keys and neither of those work also. The key fob will lock and unlock all 4 doors and the rear hatch. When the key fob locks the doors, the drivers door lock sounds a little rough as it engages. The inside lock lever on the inside door handle console locks and locks all the doors. The lock button at the top rear of the drivers door pulls up and down manually and operates without issue with both the key fob and door handle console lock lever. So the problem seems to be centered on and exclusive to keyhole. I'm a minor do-it-yourselves for repairs and maintenance in that I'll attempt a repair that's not really involved, has clear instructions and I'm confident I can complete without making the problem worse. Anybody come across this before? Thanks in advance for any ideas.

 

It's possible the rod from the drivers door lock actuator to the door lock cylinder has become disconnected if the plastic clip that holds it has broke.

Remove the door panel with the window up, pull back the plastic film and look towards the door handle with a flashlight to see if the rod is attached to the door lock cylinder. Also look to see if it's attached at the door lock actuator.