Purchasing issues

I've been using Itunes for about 7 years, without issue, but recently, when Ive been attempting to purchase music, it just sits there looking dumb.

I click on the price to purchase a song, it says its purchasing in the load bar, then it attempts to access Itunes, then nothing.

This happens, no matter which song I attempt to purchase, on my PC?

Can anyone help?

Cheers