UPVC door will not lock

[Allycee]

Can anyone help, we have had the back door open all day today as it has been so hot and now it will not lock. The door closes fine no catching etc but the handle will not lift so that the key can be turned. I have tried the locking mechanism when the door is open and everything is working as it should be. We have tried adjusting the door using the allen key but still no luck. I really don't want to be sat up all night on guard!

[alavahalf]

It's a heat thing...had this job a few times recently.
Your locking mechanism is fine, as the handle lifts when the door is open....so the problem is the door has more than likely wilted in the heat.
This in turn makes the mushrooms and rollers on the side of the door, not line up with their counterparts on the door frame.
Have you adjusted the hinges the right way...UPVC hinges often adjust in the opposite direction to what you think.
It helps to wipe a little vaseline across these locking points.Close the door and spray water across it for a few minutes..this will help it shrink back.