Hi Claude,
if you have reason to believe your ancestor is alive,
you could try www.anywho.com and do a 'Find the Person'
lookup and see if you get a hit.
You could also try Cyndi's list. Navigate to:
and scroll down to Illinois to see if the person appears in
some of the Vital Records.
Of course the person could be alive but have an unlisted
phone number or have moved into another state and be deceased.
regards,
Michael Riedel