Recovering BAK files?

When I open a project and try something I don’t want to keep, I exit without saving. This has neve been a problem. I have never lost any .BAK files until now. This time I lost all backup files, one which had some changes I wanted to undo.
Has anyone found a way to recover these files that were deleted by Cubase?
Added, I didn’t know that the drive the file was on was not protected by windows restore.

I was able to recover the BAK file using Windows File Recovery. The file size is similar to the last CPR file I saved, yet I get this message: “Invalid Project File.” I will try to do the deeper scan next. Is there something that causes Cubase to reject a recovered file?