Managing personal Outlook.com account settings, security, and privacy
Hi,
Please note that if you contact Microsoft Support, they will not be able to provide you with the changed account information. Microsoft account information is kept private for security purposes, and Microsoft Support cannot disclose or provide this information.
Microsoft Support also cannot manually recover the account because the account recovery process is designed to be fully automated.
Did the hacker change your email address? What is the exact error message you receive when you try to sign in to your Microsoft account?