Hi,
I understand how frustrating this is, especially with a long-time Minecraft account.
To help narrow this down, can you clarify a few things:
- When you try to sign in, what exact error message do you see?
- Are you still able to access your Microsoft account at https://account.microsoft.com?
- Did you receive any security emails from Microsoft about unusual activity or a password change?
- Have you tried resetting your password, and if so, what happens?
- Do you still have access to your recovery email or phone number linked to the account?