Hello nick j,
Welcome to Microsoft Q&A forum.
Before we proceed, may I know if you are able to log in to the Microsoft website or any other Microsoft apps beside Minecraft?
In the meantime, please try this quick fix to see if this helps.
- Type "Credentials Manager" in the search bar and press Enter.
- Go to Windows Credentials.
- Remove all entries:
- Contains "Xbl"
- Related to the hacked account.
- Related to your current account.
- Restart your computer.
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