Window stuck

[EdT]

One of the double glazed uPVC windows wont open. Pretty sure one of the locking bars is not retracting when the handle is turned. Any tips?

[Laurel Green]

Similar thing happened to my neighbour, only it was on a door. Luckily, it was under guarantee and, with aid of a phone call, a chap turned up within a couple of hours.

He used a thin-blade-scraper, which he forced into the closing edge, then hammered it down the length of the door to disengage the catches. He then unscrewed the locking mechanism and replaced with new.