I filed my own taxes for 2004 and 2005 however I'm no expert and I think I may have cheated myself on some valuable points. Can I refile my taxes through an expert like H&R Block or Hewitt Jackson? In both filings I did not have to pay the government and received refunds. Is there a penalty for refiling?

You can amend your returns for 2003, 2004 and 2005 using Form 1040X to get additional refunds.

For 2002 and earlier, it's too late.