I recently deleted by error a complete folder in an S3 bucket without versioning activated. This folder used to have a lifecycle policy, a lot of objects were in a glacier state. Now I can't find them, event in a vault.
Can I retrieve the deleted folder or is it a lost cause?
Unfortunately, I believe if you didn't have versioning running on the bucket to the best of my knowledge you cannot recover the items.
As stated on https://docs.aws.amazon.com/AmazonS3/latest/user-guide/undelete-objects.html
"To be able to undelete a deleted object, you must have had versioning enabled on the bucket that contains the object before the object was deleted."