Q: Problem with two front doors.

In regards to the door that doesn’t close always. The door latch mechanism can be lubricated with a spray lubricant. A dry graphie or white lithium grease are good lubricants to use. These will need to be sprayed on the moving portion of the latch in the door. Also the adjustment of the latch striker will need to be checked. Over time from repeated closing of the doors the strickers wil move inboard causing the latch to not fully engage and the door will latch shut. Before a stricker is moved its original position as far as height and inboard depth should be marked so if the new adjustment does not make a difference or adversely effects door closing the striker can be moved back to original position. The door that will not unlock situation may be a couple of things. If the vehicle has manual locks its possible the latch assembly is damaged internally and will need to be replaced. If you have power locks, the door lock switches ned to be checked and the wiring and acutaors need to be checked. You may want to enlist the help of a mechanic, like one from YourMechanic, to help in the diagnosis and repair of the door issues.