Cant log in to my account as I cant access my gmail account anymore?

Hi all, i have a subscription and an account i cant get into because i forgot my password and when requesting a new password I found out I cant access my gmail account anymore and google cant help with retrieving it as I didnt fill in a phone number and alternative emailadress. Is there a way to change the mailadres that is connected to my nextdns? Many thanks in advance.