Students keep refusing to reply to messages? What's going on here?

Maybe you did something before, enlarged it at your classmate's place, and then you found a middleman. This classmate said something to this middleman, of course, it must be something that is not very good for you, and then this classmate thought you were such a person, so he decided to draw a line with you. Personally, I suggest you don't ask. If you do, they will only give you some excuses and you won't get a real answer. In the end, you will have to take responsibility.