It should be on the backup as well.
That's what I would have thought as well, but they aren't there.
The file will be in the backup-folder's RC_Data_FMS sub-folder.
You only need to copy the file from the back-up folder to the production folder AND restore the record from the backup.
Alternatively, you can copy the entire folder over. I find that difficult as my images folder is tens of GB in size anymore.