Not an answer here --- but I just use VLC and quit using WMP years ago.

>Hi,
>
>I can't figure out how to add MP3 files to the Windows Media Player on Windows 10. I open Windows explorer, find any MP3 file and then drag it into the Music pane. Or any other pane. The cursor/icon Add to the Library appears, as I drag the file. But the file does not stay in the WMP.
>
>On Windows 7 it works.
>
>One thing I see different between Windows 7 WMP and Windows 10 WMP.
>On Windows 7 top item of the main menu says Library. That is, I have the following items:
>Library
>Playlists
>Music,
>so on
>
>On Windows 10 the top item of the main menu says my name (instead of the Library). That is, it looks like:
>Dmitry Litvak
>Playlists
>Music
>and so on.
>
>How can I make the Windows 10 WMP to be line on Windows 7?
>
>TIA