Question about WD Elements Desktop

I bought this external hard drive in 2016, so far it has run without any problems. Now I wanted to make a backup after 1-2 years, but it no longer works... When I connect the two cables (power supply and USB), I get 0 reaction (LED does not light up and nothing can be heard)... Logically, the PC does not react either. There is another power button on the back (which I have never needed so far), nothing happens with this either. (I had asked this question before, but mistakenly pressed "accept answer" on an answer that unfortunately didn't help me). Now I have ordered a new power adapter (here, of course), the product is called "CoreParts Power Adapter for WD Elements", but the plug does not fit the ext. hard drive... So I will have to make another attempt and first return the power supply etc. to find a suitable power supply. This is just to check if the power supply is the reason for the "dead HD". Has anyone also had this problem or does anyone know what the problem could be? Respectively, how can I get my external hard drive to work again so that I can save the data? Many thanks in advance :)