64 bit calibre on Windows

[Nothingness]

Originally Posted by Divingduck

calibre had never loose or delete books/library with an update. More common is, that calibre is pointed to an wrong library path. Why this happen to you, I don't know (usual this happen to users who locate their library to an network or cloud location). Check your library location (in addition if there is a file called metadata.db) and the library path in calibre preferences.

I don't know where in the options we place the location of the Library. The file metadata.db exists and is in the folder Calibre Library.

[Divingduck]

Sorry, I am a bit late...

A click on the library icon -> choose switch/create library -> first select your library location then check "use the previously existing library at new location" and finish action with Ok button.

After this your library will open correctly.

If this will not showing your library, you can try to rebuild it (https://manual.calibre-ebook.com/faq...libre-is-blank). calibre is able to rebuild the file metadata.db (make a backup first).
Assumed, you point to the correct library path, click once more the library icon and choose -> Library maintenance -> Restore database.
This action will build a new metadata.db by scanning each book path within the library folder and reading each metadata.opf. This will take a while. Take care that your library is located at your PC and not somewhere else.

[Divingduck]

Originally Posted by theducks

DD
On rare cases, the calibre config becomes corrupted during specific types of (?) upgrades and is replaced with the default.
If your Library was NOT the default name, Calibre just forgets that it (and any other) was there.

Yes, you are right. The good thing is, that this will never delete physical book files and that was, what I intent to answer. I need to be more precise...