NW 6.5 SP7 - NSS 3.26

A user have lost some files on a NSS volume.

This volume have not the automatic purge setting.

When I try to recover deleted files from user folders in Windows
explorer there is no nothing to salvage.

The volume was more 10% free space so there was no self-purge.

What could happen?

How to see all the deleted (but not purged) files ?

Is it possible to recover files even if they are not in recovery list ?