1) As a general matter, there is no right to "change your mind" after a purchase. If the seller's terms and conditions of sale allowed you to do so, then you can; otherwise, the seller can stand pat on the sale and does not have to give your money back. You need to look to the seller's terms and conditions.2) However, a seller can't keep both the item and the money; if it took your money, they have to ship you the item, or you could sue them either to consummate the sale (get the item) or for breach of contract and look to get your money back. (But again, if they send you the item you ordered, they can keep the money.)3) The only way, even if the seller does breach, to get your money or the item is to sue, which may not be economically worth it, unforatunately.