Their is a fault in the circuit. What is the switch supposed to control? Had the same thing with the circuit for the lamppost. The wire for it wasn’t buried deep enough by the previous owner and became compromised over time. For the plates, they make longer screws and also spacers for times when the box is seated too recessed. If you don’t have those on-hand, you can remove the box and seat a new one properly, but that can be a lot of trouble depending upon the circumstances.