THIS IS FOR WINDOWS10
The only place to find world saves for minecraft is through this method:
1. Right-click on the windows symbol in your taskbar.
2. Left-click on search.
3. Type %appdata% in the search bar.
4. Left-click on the folder.
5. Left-click on the folder .minecraft .
6. Left-click on the folder saves .
These are all of your minecraft worlds. if you can't find your most recent one, it is gone for good.
I hope this helps!