No adoption or birth paperwork and trying to get passport?

MissyA Asked: No adoption or birth paperwork and trying to get passport?

I recently found out that I am adopted, through a letter that my adoptive mother wrote, and as I am trying to get a passport I need to know if it is possible without adoption paperwork or birth certificate. And if it is not possible, as I do not know my birth parents names and I only had an adoptive mother, that I know of, is it possible to get a birth certificate?