Sending, receiving, and organizing email in Outlook.com
Hello,
It appears the hackers removed your email address (alias) from your Microsoft account and replaced it with their own. When this happens, the email address is permanently deleted from the servers. Additionally, if it is a Microsoft Personal domain email address, it cannot be associated with another Microsoft account or recreated.
To help prevent this situation, Microsoft always recommends that account users protect their accounts with a strong Microsoft account password and enable two-factor authentication for added security. That way, even if someone knows your password, they would still need a second verification method, such as a verification code or an authenticator app, to sign in.
Since the account (Email and password) has been changed, you cannot use the standard account recovery form. Instead, contact the Xbox Account Recovery team, which handles compromised account cases. Provide all the required information as accurately as possible before submitting the form.