Sending, receiving, and organizing email in Outlook.com
Hey there! Nice to meet you!
I'm sorry you are experiencing this.
Based on your description, your accounts were compromised. The hacker was able to remove the accounts' primary email addresses/security info and replace them with their own email address, which is why you receive the error that your account does not exist when signing in
Since the security info has been replaced, I'm afraid there is no other working method to recover the Microsoft account, and Microsoft Support cannot help either.
Thank you for your understanding.
Best regards,
Darhyl