There are certain circumstances under the IRS Voluntary Disclosure program where it may be possible to file returns without incurring criminal penalties. In most cases, IRS policy is to accept the last six years of unfiled returns as full compliance.
Incomplete records should not slow the process of becoming compliant with the IRS. Most of these records can be obtained directly from the IRS without alarm. Bank statements can help accurately prepare an unfiled return. Expense records can be recreated based on reasonable standards of your spending patterns. There are solutions to help you move on.
Believing you might owe the IRS should not prevent the filing of returns either. Solutions exist to solve unpaid tax problem, including offers in compromise, bankruptcy and installment payments.