when a document is deleted from a file cabinet, it is also deleted from the file system. This is why only Admin users should have delete rights in DocuWare.
If you have administrative windows rights on the DocuWare server, you could try to recover the file from the file system with either shadowcopy (if enabled) or a data recovery tool like Recuva. In any way you need to know either the file name, store date or Document ID to have a reliable way of knowing if what you found is what you searched for.
The other way is to restore the file from the full backup of the DocuWare server, which you hopefully have lying around on a NAS, tape or whatever kind of storage you use.
Hope this helps.
Greetings from Germany,
Simon H. Hellmann
DocuWare System Consultant