Ipod won't play some music, asks for Apple ID
My Ipod won't play a lot of my music; when I click on the song, it asks for my Apple ID and password. When I enter it, it still skips the song. It was doing just fine until today and it all of a sudden starting doing this. It's really annoying because I have over 3,000 songs and half of them won't play. It doesn't say they're in the cloud either, all of the songs that it won't play are really old and I've had them in my library forever. What could be the issue here??
iPod touch, iOS 8.2