Hi, I'm John! I will help you with this.
Do you still have access to your Microsoft account, and are you currently signed in?
Check if you still have access to your Microsoft account and make sure you're currently signed in https://account.microsoft.com/ If you’re locked out, let me know.
If you still have access, just to be safe, I’d recommend to sign out everywhere. Visit: https://account.live.com/proofs/manage/additional Scroll down to Sign me out and select "Sign me out".
In 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.
And changing your password again and enabling two-step verification if you haven’t already. This will add an extra layer of security to prevent future unauthorized access.
Let me know if you have any further questions or concerns.
Click "Add comment" to let me know.
Regards,
John J.D.