My son was born 5 years ago. His father wasn't there to sign the birth certificate. How can I change my son's last name to my married name and have my ex to sign over his rights? He doesn't see our son and our son has said on a number of times he doesn't want to see his biological father anymore. The man I've been with for almost 5 years is the only real dad he knows.

Can you get him to go through signing papers to allow guy you are with to adopt?
You should be able to go through family court to have the paperwork processed,

Get an adoption lawyer. If the biological dad does not agree, go after child support if you are not already... or give him the option to give up rights and not pay support, so the adoption can happen if that is what you want. The court may also decide in your favor if he is not attempting to make any contact... is your new husband willing to adopt? From what I've heard, courts won't allow someone to give up rights or obligations unless there is someone else willing to adopt.

Hope that is helpful.