The fix will depend on what locking mechanism you ve chosen.
How to fix french door lock.
There is no quick fix for a french door lock not working.
Spray the inside mechanics of the french door knob thoroughly using canned air duster to dislodge any dust or other large buildup.
If the french doors have dropped due to loose screws in the hinges attempt to tighten them before you test the doors again.
Open the operable door using the knob or lever handle.
Once you fix french door alignment by screwing all the hinges tight to the door frame and securing the french door jam to the rough in door opening buck plate and finally we fix french door top.
Step 3 douse the mechanics of the lock itself with spray lubricant.
The more you use your french doors the more likely the thread of the screws will drag against the walls of their casings and loosen.
From there you can either widen the hole both of the wood and metal or you can unscrew the strike and re secure it in the proper position.
Loosen and remove the machine bolts that secure the lockset at the inside face of the door using the appropriate screwdriver.
The fix a short term fix is to move the strike plate to align better with the stuck door latch.
Open the door at the side where the jamb will be shimmed and stabilize it with a doorstop.
By shutting your door you can mark the point on the door frame that latch is coming in contact with.
Turn the lock back and forth as you spray so that the lubricant can get deeper into the mechanics and allow the lock to slide free.
Nine times out of ten if the lock is stuck or if the key won t turn enough to lock your doors it will be due to some sort of obstruction in the mechanism itself.