My WD External hard drive not recognised

it’s definitely number 3 because i have never dropped it, i accidently put my laptop power cable into it for like a few seconds and then it stop working basically, but im sure my data is still intact and the HDD can be transfered to an identical case but not sure how to do that because there are two circuit boards if im right one of them is the USB/Power connecter and the other is attached to the HDD its self if that makes sense?