“It looks like someone else might be using your account” message when trying to log in.

I get this "It looks like someone else might be using your account" message when trying to access my account to check my emails. I have tried to get a password reset but I cannot access the email address the code is sent to, as I have long lost the information to it. I have tried to fill out the recovery form but was told there was not enough information to verify the account despite entering everything I could possibly remember, I have never sent an email from this account and as such cannot fill out these sections of the form, I cannot enter previous passwords because I do not remember them, which is why I had a password change in the first place, and I also do not remember the security question as it was related to my original password not the current one. I cannot afford to simply start over on a new account as many important things are linked to it as well as important archived emails I could need in the future. I need this account and I would like to have it recovered as soon as possible, it is unacceptable that I am being locked out entirely with no way to recover without it being such a hassle.