Restore the photos/folder from your backups, place it in the exact same location that the original folder was.
Your photos are not "in" Lightroom. LR just references the image files that are on your hard drive(s).
For LR to do anything with your edits, it needs access to the original image files. You will need to restore the deleted files back to the original location LR knows about (or restore the files to a new location and tell LR where the new location is).
There is nothing that can be done with the preview cache that will help you.