One of your first steps would be to contact the Illinois Adoption Registry and register with them if you have not would suggest you do so. Someone may already be looking for you. Also they can provide you with non-identifying information from your original birth certificate. However given your date of birth the information is going to be minimal - ages of birth parents at the time of your birth and they will confirm your date and place of birth for you. Another piece of information for you is that adoptions seldom took place on the date of your birth. In the 70's it generally took minimum of 6 months for an adoption to be finalized. For information on the state run registry go to the Illinois Department of Public Health website (
www.idph.state.il.us ) and they have an icon for the registry on their home page. Good Luck