This has happened to me several times, and when it does, it's extremely frustrating as I loose hours of work. In Lightroom, when you delete a photo, it moves it to the trash and any adjustments you make to that file are deleted as well. Only problem is, many times when I think just one photo is selected for deletion, all in that group have somehow been selected as well. LR does not ask you if you are sure you want to delete all 657photos, it just does it. Boom. I know you can reimport the lost photos from the trash, but there is no way to get back all the adjustment data that you spent hours doing to each photo. Why Lightroom developers have not addressed this catastrophically stupid oversight is beyond me. Every software program in the universe has an undo delete feature, except Lightroom. Does anyone know any work arounds to prevent this for happening again? Lightroom is very touchy about select all/select one and this has happened to me 8 or 9 times now.
LR does not ask you if you are sure you want to delete all 657photos, it just does it.
Are you deleting the photos by hitting the Delete (Mac) or Backspace (Windows) key? If so, it should be asking you to confirm the deletion:
Or are you using the Cmd + Opt + Shift + Delete (Mac) or Ctrl + Alt + Shift + Backspace shortcut, which deletes without any confirmation?
If you turn on the option Catalog Settings > Metadata > Automatically Write Changes Into XMP, then you develop settings and other metadata changes will get written to a .xmp sidecar (for raws) or into the file itself (non-raws). Then when this happens again, when you recover the photos from the trash and import them into LR, your changes will get recovered.
Also, please add your me-too vote and details of why you want this to the feature request in the official Adobe feedback forum: Lightroom: Cannot undo delete | Photoshop Family Customer Community . The more people who add their opinion, the more likely it is Adobe will consider implementing it.