On doors where there is a multi point locking system this can be a sign that the system has been worked too hard.
Multipoint door lock jammed.
Usually a simple spray of lubricating oil on the working parts is enough to sort out the problem.
To rule out any problems with the cylinder try inserting your key and turn to unlock.
When you are trying to figure out how to fix a door lock that is jammed it is necessary to stay patient to avoid causing further damage.
It can also indicate the cam has become worn.
The bottom hook has slipped out of it s adjustable teeth if it has them which hold it in place for different size doors.
It could be 1 of 2 things.
Then insert a small screw driver awl etc.
A door lock can also start jamming due to a lack of lubrication.
The wood can be removed from this area to expose the slot.
A broken key extractor is one of the easiest ways how to fix a door lock that is jammed in this way to open.
A multipoint lock that is engaged when the handle is lifted if your door is misaligned or if there has been excessive pressure placed on the door then it can cause damage to the locks.
I am showing how to disassemble and free a jammed sash upvc lock.
If the teeth connected to the bottom hook are not in the right position then lifting the handle will not bring the hook completely out for you to open the door.
If you do not have a proper broken key extractor you can use a jigsaw blade or a pair of tweezers.
The bottom of the vertical slot is about 1 inch above the thumbturn cylinder slot and abou 1 4 inch off center towards the latch side of the door.
This problem with the multi point locking system can develop over time until the lock suddenly stops working.
Sometimes the pins and levers inside a lock become so dry that they stop moving smoothly and eventually seize up.
Definitely not the fault here was the multipoint mechanism this is the long locking strip in the edge of the door and in this case the gearbox the center case in the middle of the locking strip i carry most multi point gearboxes so it was simply a case of replacing the part in the door.
Pictured below is an example.