Can't remember the name of an old romantic comedy.

So basically this movie is about a poor man who comes to work for some rich person and he stars off by cleaning windows. This rich man has a naughty son who always humiliates this poor man. Also, this poor man is in love with some girl who works for that rich person too. Then, this boy wants to leave his home and so he does by hiding in that poor man's car. Later on, he gets kidnapped and the poor guy finds him and kicks the kidnappers' asses. Then, he marries that girl. PLEASE HELP! This is such an amazing old comedy and I'm not really sure if it was black and white, but it was NOT a silent movie. Thanx a lot.