When the guest came to our hotel, he was very angry and unhappy. What should you do if you are the waiter who receives him?

If you don't know him well, let him say it first, otherwise others will think you look familiar (some people don't like it). Once he says it, it proves that he doesn't want to take this breath-holding thing to heart, so you should "play it by ear" appropriately. If he is talking about someone who makes him angry, then you should demote that person appropriately and cook him without trace. That's how you can get up there.