I don't know what a "cleanup scan" is (some Samsung feature, or a third party app?). If deleted images were on a removable sd card then you can restore them by sticking it in a card reader, attaching that to a computer and using any file recovery software you like. Don't use it inbetween or you may overwrite them. If they are on internal storage you've probably no way of recovering them.
However from your screenshot it looks like the images are still there, just the thumbnails are gone. Most gallery apps will rebuild those anyway, but have you tried just opening them with a gallery app, a file browser, or copying/sending some elsewhere and seeing whether you can view them there? It may be just the preview that has gone.
Can you tell us exactly what this "cleanup scan" said it was going to delete? It's always a good ide to check rather than just accept all suggestions from cleanup utilities.