Americans mostly overpay taxes during the year. A tax refund is the money people usually overpay the govenment during the year that the government pays back to you. If you overpaid, and if your tax returns were filled out correctly then you would automatically get a refund check from the government.
Most importantly, you need to speak with your account and learn more about your taxes. Don't assume that just because they're an accountant, they know exactly what they're doing and what you're up to. If you don't like that account or if they're not communicating with you directly then you need to hire a new account.
If you are owed a refund from tax year 2006 you will need to file an amended tax return for that tax year. I would advise taking all of your tax paperwork including a copy of your return to a new accountant for assistance. You can also use tax software with your original paperwork (W2, 1099 and other tax information) to determine what, if any amount, you may be owed.