When you're ready to reactivate your account, you should be able to sign into your account with your email and password to reactivate it. If you used a third-party sign on option instead of an email and password combo, or run into any other trouble, please reach out to our support team at support@brilliant.org, and they'll be happy to reactivate it for you.
Unfortunately, if your account has been fully deleted, there's no way to recover it, or any of it's associated data.
Still have questions? Reach us at support@brilliant.org.