If they have already released those bitcoin out of escrow account than you can't do anything, this is the reason why you shouldn't trade with any people with 0 trades and low total trade volume. Always look for feedback of the buyer, if you are selling than you have to be more careful before trusting any newbie traders.

Yes screenshot can be faked using photoshop and there are many scammers in localbitcoins that lure sellers with high market rate and scam others by fake screenshots.