Hello, I’m Virginia a fellow Windows user.
If the account shows that it doesn’t exist then chances are it was closed due to lack of use. As for the 30 day wait to change your details this is a security feature & cannot be circumvented nor speeded up so your only option is to await the 30 days.
It’s recommended to have at least 2 recovery options - Authenticator app &/or sms/text - in case 1 fails. Once access is restored I’d recommend adding a 2nd recovery method & saving the MS account’s recovery code as well which would restore access if all 2fa ever fails.