so minecraft 1.12.2 on my pc said it could not locate javaw.exe runtime so i put it in the .minecraft folder and when i did it delete everything why?

The title says it all, but when I looked int the .minecraft/saves folder the worlds were still there! And now everything except my account is deleted.(including launches, worlds, skins, and servers) 

Well now minecraft works but I've tried getting the files the other report said that fixed it but there was none of that name. I've also tried making a duplicate of the worlds but that didn't work either. Everything is still deleted.