Well, that is bad news.
While not exactly what you did, this FAQ still applies as the remote might have done it.
https://manual.calibre-ebook.com/faq...rked-drive-nas
Calibre (GUI) is not designed for multiple access. For sharing, run the content server, with the PC being the host (and control).
Just to Clairfy. YOUR PC drive was where
Books was?
The folder is still there? Do you still have 'Rights" to the contents (might just be hidden)?