Hi Andrej,
you can restore a complete data backup which includes the deleted files. All changes which habve been done after the backup has been created are logged in the log area. If you know when the user deleted the document by mistake you can use restore log until to stopp just before the delete was executed. But you will loose all changes which have been done after the delte of the document by mistake. This is scenaario is called pint in time recovery.
If a delete of documents is commited then the database system is changed -> deletes the document. I
This is normal behavior of databases.
I know that content server allows to store documents twice on database level and on file system level. If you still have the missed document on file system level you can relaod it into the database.
If you have another content server which includes still the missed document you can use loadercli to download the missed document and reload it into your system where the document is missed. To get help in this issue please open an OSS ticket on BC-DB-SDB.
Regards, Christiane