My Cloud disk back up

Hi Everyone

I need some help, over the past few years we have been using a mycloud 4g device no probs - Ive routinley backed it up to a external wd hard drive. A few weeks ago I notice that my kids had been playing around with the mycloud 4g and it now has a constant red light. Deciding that I needed to replace the drive I purchased a myclud ex2 ultra thinking that I could use the external wd hard drive to retrieve the data stored originally on the mycloud 4g. This is not the case as the backup is different - is there someone who knows help. PC also does not recognise the external wd hard drive?

What is a My Cloud 4g, and I haven’t seen anything about a My Cloud Home? What external wd hard drive do you own?