Hi Manoj!

By SSC Seat Number, I guess you are trying to mean Registration Number. Correct me if I'm wrong. Anyway, if you forgot your Registration Number, no problem, go to the Official Website where you registered yourself for the Exam. Type in your registered Mail ID and password, it will take you to the Application Form where you can view it. If you have also forgot your Mail ID and Password, then there is one more option. Go to the same Official Website and it will ask details like your name, your father's name, date of birth which will search and give you an option to download your Admit Card where you can view your Registration Number!

Hope this is helpful!

All the best!