To rule out any problems with the cylinder try inserting your key and turn to unlock.
How to open patio door locks.
If the locking mechanism is a latchbolt the kind of bolt that is spring loaded and has one angled edge and the angled edge is facing away from you you can hook it with a wire hanger.
Take an allen wrench and loosen the set screw under one of the handles.
Sliding glass door handle set 6 5 8 in diecast and wood hook style flush mount keyed this is a reversible diecast black flush this is a reversible diecast black flush mount patio door handle with wood pulls.
If you both pull the handle will come off one side and the handle and spindle will come off the other side.
The door originally came with a temporary handle which is a square rod that is bent 90 degrees.
On a wooden patio panel a pocket is milled out of the sliding panel frame and a mortise lock is slid in.
Remove the two screws that hold the lock faceplate on the edge of the door.
If your door is misaligned or if there has been excessive pressure placed on the door then it can cause damage to the locks.
This is designed for acorn and better bilt doors but can be found on a variety of other door manufacturers.
Tilting the door lowers the latch releasing it from the bracket.
The handleset is installed and the lock actuator rod is slid through a hole in the frame into a hole in the seperate mortise lock.
Mortised locks fit right into the frame of the door.
If it turns freely and unlocks then the problem may lie in the multipoint lock.
And this will need replacing.
For most doors especially doors that have been in place for a few years you can put push against the door then using pressure life and drop the door a few times.
With the door open use a phillips screwdriver to take out the two connecting screws that are located by the doorknob on the inside of the lock.
Have one person go to the other side of the door and hold the handle.
Insert a screwdriver or pry bar between the door frame and the door about 6 inches from the corner diagonal from the latch at the bottom and pry upward.
After literally a few seconds the locks tend to fail to the point where you can simply slide the door open and gain access.
Slide the doorknob off the spindle pull out the lock mechanism and remove the latchbolt from its hole in the edge of the door.