Riot Account Help

I was recently forced to change my League Of Legends Log In to something else because of the change riot made (for some reason?). I now cannot log into my account, The only things I know are my in game name and my password, and was wondering if a rioter or someone could help me with knowing what my new username is? I have been playing this game for 9 years and now I cannot log in because my username was forcibly changed to something else. I would love to be able to log into the account, but do not know the username and the email is so old that I can no longer access it.