Why didn't the instructor reply to my message?

First of all, maybe the teacher was busy and didn't see the message you sent in time. Because as you said, the instructor's business is very busy every day. Maybe he didn't see the message you sent. You can wait patiently or send another message to the teacher. If you are in a hurry, you can call to communicate. After all, calling is much more reliable than sending messages.

Second, the teacher may not be able to deal with your problem for the time being, and he is also looking for a solution. Sometimes the tutor can't solve your problems. He needs to report to the top or find a way to solve it. You can wait patiently and watch it later.

Third, the teacher may have seen it and didn't reply or other reasons. If you don't reply to the message for a long time, call for advice. After all, there are many defects or deficiencies in sending messages, and telephone communication is better.