i downloaded an album but one of the songs only plays for a few seconds then skips to the next song. how do i fix this?

Depending upon what country that you are in (music can't be re-downloaded in all countries) then try deleting that track from your iTunes library and redownload it via the Purchased link under Quicklinks 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