How can you upgrade from from Microsoft windows server 2003 to 2008 R2 or 2012 without loosing any data?

Use the following link to upgrade Windows Server 2003 to Windows Server 2012. I've used it to upgrade 2 of our AD and it works perfectly:

http://blogs.technet.com/b/canitpro/archive/2014/11/12/step-by-step-migrating-the-active-directory-certificate-service-from-windows-server-2003-to-2012-r2.aspx

https://technet.microsoft.com/en-us/library/ff972408%28v=ws.10%29.aspx