If you haven’t played Club Penguin Rewritten for some time, when logging in you’ll be asked to re-verify your Account. Which will be sent to your Email that you used to create your Penguin, but some players don’t receive the email. This could be a number of issues, one being that it went into your Email’s Junk folder. Could also be that you are using the wrong email, which a good way to double check is to submit a Forgot My Password, plus that will fix the Verifying your Penguin.
Now if none of these work, give it at least 24 hours then I would suggest sending the Club Penguin Rewritten Support Team an email to “email@example.com”. Also remember that emails from the official Team end with “@cprewritten.net”, any others are fake.