My parents weren't able to claim me as a dependent, can I refile my 2007 taxes as an independent?

My parents had initially claimed me as a dependent, but it turns out that they're unqualified to do so. I already did my taxes and received my refund check. Can I refile my taxes and receive the money that I was suppose to get if I had UNCHECKED the question that asked me if I can be claimed as a dependent on someone else's return? And will I now be able to receive a tax rebate check?