What does it mean to end a sentence in 没?
"你找到你爸爸了没"


It's short for "你找到你爸爸了没有?" or "你找到你爸爸了还是没有找到?". The complete sentence should be "do you find your father, or not?". "没" here is similar as "or not" in English.

BTW. The "你" before "爸爸" is redundant in Chinese. "你找到爸爸了没" is correct. It is impacted by translation from western language. Even many Chinese make this kind of mistake too.