Couple of questions... First I would like to try finding my father's birth mother/father, but the problem is he does not even have his birth certificate. He only has a photo copy. The other problem is he was actually adopted twice... his first adoptive mother died and the father could not care for my dad by himself.
Second, I don't have much information I know my dad was born in Denver on January 8th 1947. I have not really done any looking yet so I was wondering where I should start? My dad did not want to look for his birth parents while his adoptive mother/father were still alive, and they did not have any information to give him other than what they were told.
Any help you can give me would be helpful.

There's numerous problems you will encounter, including:

The time that has passed will cause problems with record keeping
The fact is was CLOSED, going by your own title.