I can't see the books on my Kindle PaperWhite

I can't see the books on my Kindle PaperWhite.

It started when I stupidly copied a book across manually using Widnows rather than Calibre.

I have since factory reset the device, whcih I would epxect to undo any harm I had done.

But when I use Calibre to download again the books do not show up on the Kindle book list (they are present on the device if I look at it as a Widnows drive).

Can anyone help? I can't use my Kindle at all :-(