To clear storage space in order to upgrade to iOS 8, I went to Settings/General/Usage/Manage Storage/Music on my iPad and deleted all my music (I have it all stored in iTunes on my Mac at home.)
I got the space back and installed iOS 8 over-the-air. But now when I go to the Music app, it looks like my music library is still there—the metadata (including album art) still shows. When I tap on a song, the name greys out and a "Stop" icon in a circle appears on the right hand side of the table.
(When I go into Settings/General/Usage/Manage Storage/Music, it tells me all my songs are still taking up 41.2GB, and lists each artist with their individual usages.)
How can I force the iPad to dump and regenerate its cache of Music.app metadata?