Microsoft began hiding libraries from the File Explorer’s navigation pane on Windows 8.1, and they’re still hidden by default on Windows 10. This is weird, because libraries are still used by Windows. The Photos app uses your Pictures library, the Groove Music app uses your Music library, and the media sharing server shares the contents of your media libraries, for example.
To unhide your libraries, open a File Explorer window. If you don’t have a File Explorer window open, you can quickly open one by pressing Windows+E.
Right-click an empty space in the left pane and select “Show libraries”.
The libraries will appear in the left pane, exactly where they were on Windows 7.
You can now use libraries exactly like you could on Windows 7. Right-click a library and select “Properties” to manage the underlying folders included in the library view.
That’s it! The libraries will also appear in the Save As and Open dialogs when you show them here. If you ever want to hide them, just right-click in the left pane once again and uncheck “Show libraries”.