thanks and found nice information

Thanks guys for all the nice suggestions, I just got some more information from the web, want to share with your guys, in case of birth certificate is not available, you need to submit "non-availability certificate" from the same place you would get birth certificate, and two sworn affidavit from your parent and relatives. You can find letter samples at:

http://www.immihelp.com/immigration/birth-certificate.html

In cases where birth certificates from the authorities are unavailable or contain insufficient information regarding the birth or the parents, a sworn affidavit executed by either the parents, if living, or other close relatives older than the applicant, may be submitted. It should set forth the relationship between the deponent and the applicant, how well the deponent knows the applicant, date and place of the applicant's birth, the names of both parents, and any other related facts. Such affidavit, when a birth certificate is unavailable, should be accompanied by a document from a competent governmental authority confirming that the certificate does not exist, or no longer exists.