Hi, I'm John! I will help you with this.
May I know what troubleshooting steps have you already taken? This will help me avoid recommending them again.
Have you already checked Outlook rules?
If you haven't tried it yet, please go to https://outlook.live.com/mail go to Settings > View all Outlook settings > Mail > Rules and Mail > Forwarding to make sure no one has set up rules to forward or delete your messages.
If the issue persists, please provide more details by answering my questions.
Click "Add comment" below to let me know.