I lost the connctn with my 2 chldrn in Chicago 1n 92 when a terrible divorce happnd Who can help or tell how?

My Son Ashkan (now 28) and my daughter Shadi (now 24) where in Chicago in 1992 when my Ex has filed a petition for divorce and she of course received the custody of our youngsters in my absence.She moved to Indiana after I departed from the states before court order.I really miss my children after all these years.I have indirectly heard that my ex has changed the names legally.