Visit the website, Germany-Service.com, it is your personal support in Germany for obtaining your German birth documents, they charge $69.00 US dollars for their service.

http://www.germany-service.com/birth_certificate_germany.htm

You can also:

Contact the Germany Embassy and ask for their help, or obtain a copy of your birth certificate from the health department. Contact the health department in the county of your birth for an official copy of your birth certificate. This is the primary document to prove citizenship.

http://www.bmg.bund.de/cln_110/DE/Ministerium/ministerium__node.html?__nnn=true

The Ministry of Health website is written in German.