It's difficult to tell going by the pic, is that the ground floor? If yes, and assuming the locks are in the unlocked positions, you should be able to manually manipulate the window back into the frame and lock it, either by going outside and/or holding the handle. In short, jiggle it about
When it's nearly closed go outside and give the top corners a gentle thump while someone inside pulling with the handle
What's happened is the pointed parts on the hinge at the top is not locating in the receiver cup but rather it is riding outside of it hence the gap in the window when it gets to that point where it jams up
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