How do I help my friend?

My best friend and other friend got into an argument and they aren’t talking. My friend likes my best friend but she doesn’t like him back. Yesterday The cops founds my friend’s best friend with a gun to his head about to kill himself. Now my friend is all depressed and won’t talk to anyone except my best friend and me but like I said my best friend doesn’t want to talk to him at all. I keep trying to get her to talk to him but she won’t listen to me. How do I get him to get himself help? I’m really starting to get worried about him and I don’t know what to do.