Using classic Outlook for Windows in business environments
Dear Seb Smadja
Thanks for using Microsoft products and posting in the Community.
If you find that you can't log into your account, it means that your account has been stolen by a hacker who has changed your password. If you find that your binding email give and cell phone are not your binding email and cell phone, it means that the hacker has also changed your binding information.
For this situation, you need to contact chat immediately to recover your account, you need to fill in as much account information as possible to prove that you are the account himself, if you don't have another Microsoft account, you need to apply for a new Microsoft account to recover your stolen account. I hope you can successfully recover your account, good luck.
You can try logging on to the following website
Contact Us - Microsoft Support
Enter your details of the problem e.g. msa.
Then tap Contact Support in the bottom left corner.
Choose from the following categories: Other Products, Manage Account Security.
TIPS: Please contact us during local working hours on weekdays, CHAT does not work 24 hours a day.
Best wishes
Clark | Microsoft Community Support Specialist