Q: why was i charged for a song when I do not own a iphone anymore

We are fellow users here on these forums, we won't know what the charge was for.

You can view the purchase history on your account via your computer's iTunes : og into your account on your computer's iTunes via the Store > View Account menu option, you should then see a Purchase History section with a 'see all' link to the right of it. Click on that and you should then see a list of your purchases.

You amy also want to check to see if you had any auto-renewing subscriptions that you hadn't cancelled : http://support.apple.com/kb/HT4098