My girlfriend doesn't answer the phone, send messages, reply or tell me what the breakup is about. What kind of message should I send to care about him?

There are two situations. One is that you may have done something wrong to make her unhappy, so you deliberately ignored you. At this time, you should first find out what you did wrong, and then coax her slowly. In the second case, she may not answer you because of something, but it seems that she has been listening to your questions for more than a day or two, so the second case is less likely. If this is the case, you can choose to find her good friend and ask for information confirmation.