Welcome to Android Central! Who factory reset your phone?
Your Google account and password are crucial to remember if you want to do anything with Android phones, so it's imperative for you to remember it. In the future, if you have trouble remembering things, you can always write the information on a piece of paper and keep it somewhere secure, like a safe.
See if this helps at all: https://support.google.com/accounts/answer/7682439?hl=en