iTunes won't work after updating to iOS 8.3

After updating to iOS 8.3 my iTunes App on my iPhone 6 Plus and iPad Air now both don't work.

If I go to play an sample of a song, the little square box with the cover on spins around and then spins back around and no music will play. I'm all so unable to play any music that I've already purchased via iTunes on my iOS devices.

Any comments on what could be causing this?

All so, on another note. My friend has just updated to IOS 8.3 and he just noticed that he no longer even has the iTunes App on his iPhone 5.

Thanks.