I have his full name and his birthdate... but all the search for people sites on the internet have not been able to give me any correct information...

Have you tried yellow pages and calling a million numbers? You never know, if you know th general area where he lives then you'll have a better chance. Also, if you have enough money you could probably hire a private investigator. Just keep in mind, that once you find him, you might not like what you find, or you could be plesantly surprised. Be prepared for any reaction and good luck.