Managing personal Outlook.com account settings, security, and privacy
Curious how you know the account still exists, because if the account is not used during the last two years, typically it is gone per Microsoft's inactivity protocol. Did you try to log in and it didn't give you the "account no longer exist" error?
If it prompts you for recovery method, it means the account has 2FA enabled, in this case, filling out a recovery form is moot point according to https://support.microsoft.com/en-us/accounts-billing/manage/help-with-the-microsoft-account-recovery-form
As the second bullet in the screenshot says, if you don't recognize the verification method and want to try to reset password, use the sign in helper: https://support.microsoft.com/home/contact?linkquery=Help%20me%20sign%20in%20to%20my%20Microsoft%20account
To set up expectation, those are the ONLY two pathways, if applicable. No one in the community forum can interfere or make such a decision but rather point you to available tools you can use.