New and revised info for this answer - There is a case pending right now before the U.S. Supreme Court that may have some bearing on your case. It is Astrue v. Capato. The Court heard oral arguments in mid-March ... a decision should be issued by June 2012.
If you go to this link you can locate an experienced professional in your location, or at least in your state. If this doesn't work, I strongly recommend Legal Aid or the legal clinic of a Law School in your area or State.
Do not give up hope. There are other methods that can be used. I once successfully represented a mother of three children and used verified statements from deceased's mother, mother of children, friends, and relatives of the father. We did not have or use DNA, It is not the only way.
Keep hope alive!
Answered on Mar 13th, 2012 at 7:35 PM