If you no longer have access to your email, but remember your password, you can log in with your email and password. Please then go to the Account Settings to "Change Your email address"
Otherwise, if you have registered a phone number to your IMDb account, you can reset your password using your phone number. Please see How do I reset my password on the mobile site?.
On the other hand, if you no longer have access to the email you used to sign up with IMDb, and no phone number is registered to your IMDb account, please contact Customer Service to get help recovering your account.