Q: I bought a song on iTunes set this world on fire by the janoskians and it won't play it

Depending upon what country that you are in (music can't be re-downloaded in all countries) then try deleting the track from the Music app on your iPad (swiping across the track on the selection screen shoudl give you a Delete button) and redownload it via the Purchased tab in the iTunes store app, or if you are doing it on your compute's iTunes then delete the track from your library and redownload it via the Purchased link under Quick Links on the right-hand side of the iTunes store home page on your computer's iTunes.

If you aren't in a country where you can re-download music or if it re-downloads with the same problem then try the 'report a problem' page to contact iTunes Support : http://reportaproblem.apple.com

If the 'report a problem' link doesn't work then you can try contacting iTunes support via this page : http://www.apple.com/support/itunes/contact/- click on Contact iTunes Store Support on the right-hand side of the page, then Purchases, Billing & Redemption