You haven't mentioned which State Application login credentials did you forget. Every State has its own CET and so you need to mail them at their respective  helpdesk. For example, if it is regarding KCET, if you have already checked your Inbox and text messages, then you  have to mail the helpdesk at their email id: keauthority-ka@nic.in (mailto:keauthority-ka@nic.in) . But if you are not from Karnataka, then the procedure remains the same but the mail id changes.