Since you need immediate help you shouldn't wait for a reply on this forum as most people are just users trying to be helpful and not Stubhub reps. Call 866-788-2482 or send a message to @TeamStubHub. Stubhub is a mess right now so I hope that you get this resolved.
We are changing the way you register and sign-in to the StubHub Community. After the switch, you will enter the email address you use to access the community in order to reset your password. You will enter your community username and new password and done!
