I picked up a client this week that hasn't file since 1994.
You have three years to file if you want your refund. After three years you lose the refund, but still must file. If you owe money, you owe until 10 years after the return is filed. In other words, once you file, the IRS has 10 years to swing at you to collect a balance due before it goes out of stat. You only have three years to swing for your money.
Now go file those back returns. And send the returns close to falling out of stat certified.
Oh, and unless there is fraud involved, forget the attorney. Get a tax pro; a CPA or enrolled agent is more than fine.