But, there is always a chance you might get lucky. Your index search may have turned up a few genealogy sites. Some military base sites have locator search engines that will give you the work address and phone for the employees on the base, military and civilian. If you cannot find a locator, but can do a search, search for the person's name. You may find them listed on a document they have published or on a list of orders approving officials.
Similar sites exist for county, state and local governments.
Your subject might belong to a professional association for his occupation. There are similar sites for other specialties from librarians to teachers. Then there is a whole other category of missing children. Usually these are folks who don't want to be found or someone doesn't want them to be found. There are also address lists that exchange messages about missing people.