Having a bit of trouble with my wallpaper!

Hiya, I've just recently changed my background to a pic of my baby girl, it
was fine until I next came on the pc, now she's got a big white square box
over her face and I don't know how to get rid of it. Tried changing the
wallpaper but the box doesn't budge. Anyone know why or what to do?? Ta x
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I''m useless with computers, but I make a mean roast dinner...