Can I assume you placed an order through Apple? You didn't actually give much useful information in your question.
If you placed the order through apple.com, then yes, you can print out the receipt from your account on apple.com. If you called the order in, I'd call Apple. If you went to the store, they can possibly pull up your receipt for you if you call them.
If I'm completely off, if you give us some more information, we can probably try to help.