what do you say?

I'd really like to know what a person should say to someone who isn't just discouraged, but losing hope.

I know how to encourage discouraged people, but when I encounter hopelessness I'm speechless. Is there a level above encouragement that I can tap into? Cuz I find that when I encounter a hopeless person my initial reaction is to change the subject. The heaviness over the person wins because I can't think of a response that is good enough, that will make things better, that will lighten the mood.

I'd like to make a difference in these people's lives, but I've hit a road block.

HELP!