Before we look at how to repair a latch here is a note regarding all issues with upvc door latches or mechanisms.
Latch mechanism stuck in door.
To take yours.
You should first test the door latch to ensure the latch is sticking inside the door and not due to a misaligned strike plate.
Turn the knob to open the door and release the knob slowly.
If this works then you can open the door and it s time to replace the dead latch.
You may want to spray wd40 or other lubricant on the lock mechanism.
A sticking door latch might require some lubrication or it might be jamming against the strike plate on the door jamb.
If your upvc door is stuck shut or if you are having problems with the door you may need to contact a locksmith that offers upvc door services.
Taking the lock of the door is often simpler than it would be to take a deadbolt or exterior door knob lock of the door.
Take the latch and knob off of the door and clean them.
Jammed upvc door locks and latches.
You can see where the cylinder entered the dead latch mechanism and pulled the latch back.
This is because the issue is not with the door and not even with the control the knob has over the stuck latch.
On the kwikset locks this looks like two little teeth that the cylinder pushes back.
First off if you can see and interact with the stuck lock button you will be able to address the set screws or twist off rose.