My Microsoft account primary alias was changed without authorization and my original username was deleted.

Question

My account was compromised by an attacker, I tried logging into my account but it told me "We couldn't find an account with that username. Try another, or get a new Microsoft account.". and I think my Microsoft account primary alias was changed without authorization and my original username was deleted.

Answer 1

If the original username now shows "We couldn't find an account with that username", the sign-in alias may have been changed or removed from the Microsoft account.

Use this recovery path:

1. Start with the Microsoft account Sign-in Helper. Microsoft states that if the username is not recognized or the account appears not to exist, the Sign-in Helper is the correct next step.
2. If the account was compromised, use the hacked or compromised account recovery flow. That tool can either show self-help steps or offer the chance to talk to an agent.
3. If access is regained, immediately:
   • change or reset the password
   • review account settings such as connected accounts, forwarding, and automatic replies
   • scan the PC for malware before changing the password
4. If an alias is still available for the account but one alias was blocked for sign-in, use Forgot your username? to identify which aliases can still sign in, then sign in with an alias that is not blocked.
5. If support is needed, contact Microsoft Support through the public support flow. Microsoft notes that support agents cannot send password reset links or directly change account details, but the support path can route the case appropriately.

Important details for this scenario:

• When an alias is blocked for sign-in, the error "This username has been turned off for sign-in. Try a different one." means another alias on the same account may still work.
• If the original username is no longer recognized at all, Microsoft specifically directs that case to the Sign-in Helper.
• If the account was recently taken over and the primary alias was replaced, keep any Microsoft security notifications and be ready to provide previous account details only through private support channels.

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References:

• I can't sign in to my Microsoft account
• How to recover a hacked or compromised Microsoft account
• How to fix "This username has been turned off" error
• What happens if there's an unusual sign-in to your account
• Microsoft account compromised: primary alias changed and original email no longer recognized - Microsoft Q&A