I can't download apps My question is how cancel items in your AppStore ?

We are fellow users on these user-to-user forums, you're not talking to iTunes Support nor Apple.

Why can't you download apps ? If you getting a message about a problem with a previous purchase then that implies that iTunes wasn't able to collect the money for your last purchase and that you therefore owe iTunes money - if that is the case you will have to pay what you owe before you will be able to download anything else : Pay an unpaid balance in the iTunes Store - Apple Support