locked out of apple account. trying to change password. trusted phone# is this phone. Notification not showing when phone# entered

I got locked out of another Apple account (not this one) after trying many passwords. Am trying to change the password. When asked, I entered the trusted phone# which is this phone. Message says use the notification sent to the "other iphone" to reset password. The trusted phone number is THIS iphone, there is no "other" iphone. No notification arrives on THIS iphone. I'm stuck in a loop.