Friend thinks he's a failure...

Last night I and my friend Jugger were roleplaying, we were having such a great time... He was interrupted every few minutes and the RP slowed to a crawl. Eventually, he fell asleep in the middle of it, but now blames himself and thinks he's a failure. He's now depressed and now back to school after a week's break. I want him to be back to his old self, see him smile. I feel so bad for him when he's like this, every time he really wants to get into it, something comes up that ruins it. What can I do or say that will make him cheer up?​