Try logging in with any email address that you own - the majority of members reporting this login message forget that they signed up using their work email address (don't worry, it happens to all of us!)
If you have access to the email address on your account, try resetting your password; guidance on how to do that can be found in this article or this YouTube video
If you're struggling to log in even after changing your password, please submit a request by clicking here.
If you no longer have access to the email address on your account, submit a request to change your email address here (under 'What would you like to manage', select 'Change my details')