This one is easy. File your past due tax returns ASAP. As your tax professional to include the Installment Agreement Request if you owe the IRS. Tell your tax professional how much you can pay each month (remember penalties and interest should be added in) and on what day of the month you want to make your payment to the IRS.
This won't get rid of the Levy, however, if/when the IRS accepts your Installment Agreement, (which will cost you around $100) you won't have any bank or wage garnishment surprises, unless you fail to honor your agreement with the IRS (Please visit http://www.irs.gov/ for exact tax codes - there are stipulations)
However, you may not owe the IRS, they may owe you. You never really know, until you complete the past due tax return.
We prepare past due tax returns for years as far back as 2000 for Federal tax returns.