Account Recovery

My account has been deactivated by Riot (not banned). They are asking me for the original email address for the account. I don't have it because the account was given to me by a friend several years ago. I am no longer in contact with this person, so it is not possible to obtain the email address. I am the only one who has ever played on this account for years, but I no longer have it.

Do you have a solution for finding the original email address for the account without going through Riot, who won't give it to me?