Powerbook g4

Hello

I went into apple fairview and asked them to factory reset my powerbook g4 because I couldn't remember my password but they said because its old they will just reset the password because resetting everything will cause a lot of errors to occur and add more problems. So now as he reset the password the username disappeared and I couldn't remember the username (sigh...) so now I am stuck in the log in screen. What can I do now?