Managing personal Outlook.com account settings, security, and privacy
Hello @Mohammad Abdo
Yes, recovery may still be possible even if the attacker changed the password and account aliases, but you'll need to go through Microsoft's account recovery process. Microsoft Q&A users and moderators cannot manually restore or change an account's ownership.
Since your original email now reports that the account doesn't exist, start with Microsoft's Sign-in Helper. Microsoft specifically recommends this when a previously working username is no longer recognized.
Microsoft Account Sign-in Helper
If you're directed to the account recovery process, provide as much historical information as possible. Useful information can include previous passwords, Outlook contacts and exact email subject lines, Skype information, Xbox console information, and other details associated with the account. Microsoft recommends completing the recovery process from a device and location you've previously used with the account when possible.
Microsoft – Help with the account recovery form
If Microsoft still reports "We couldn't find an account with that username," Microsoft also provides a support route specifically for cases where a previously working username has stopped working.
One important limitation: Microsoft Support cannot simply change the account details or send you a password-reset link. Microsoft states that support agents aren't permitted to access and change account details on users' behalf, so you still have to establish ownership through the account recovery/security process.
Since you mentioned that several other accounts and email addresses were compromised as well, I'd also secure those accounts and devices before resetting credentials. Microsoft recommends performing a malware/security scan before changing the password of a compromised Microsoft account.
Microsoft – Recover a hacked or compromised Microsoft account
Also, please don't post your email address, old passwords, recovery codes, phone number, or other account-verification information publicly in this thread.
I would start with the Sign-in Helper and let us know what it shows, for example, whether it says the account doesn't exist, recognizes another alias, or directs you to account recovery. That will determine the next step.
Please "Accept the Answer" if this information helped you. This will help us and others in the community.