If you no longer remember which username or email address you used to log in, click on "Forgot password?" Go to the login page of your school.. 

... and in the next step on "No e-mail address given?".

On the next page, please fill out the password reset form and click on "Reset password". In the next step you will receive an email with your new access data.

If you did not provide an email you will be required to contact your Sdui contact person.