Hi and welcome to forum :)
you will have to contact support about this , asking for giving it back and take the gold you got
this is how to contact them
https://forums.socialpointgames.com/topic/30/how-to-report-game-problems-to-support

@Bala-Rajesh Btw, they may or may not give it back. Ask very nicely to improve your chances. This is also a one time thing as well. If it happens again, they usually don’t refund a second time.