Verwalten persönlicher Kontoeinstellungen, Sicherheit und Datenschutz für Outlook.com
Hello,
Unfortunately your account is actually gone. According to Microsoft's account activity policy, if you haven't used the account in the last 2 years, they would close the account.
And because Microsoft doesn't allow the reuse of its native domain address, hence you get the "email already taken" if you try to recreate it.