Generally - if you did not have any income in 2002-2006 you was not required to file tax returns for those years.
You would be required to file if you has self-employment income above $400 per year or
other taxable income (for singles)
2002 - above $7,700
2003 - above $7,800
2004 - above $7,950
2005 - above $8,200
2006 - above $8,450
If you got a notice from the IRS about not filing tax returns for 2002-2006 - I suggest you to write them back that you was not required to file - do not provide any details or explanations.
You do not need to hire an accountant or lawyer for this.