Adobe CS4 Creative Suite (Student Edition). How can i now get the serial again with the "voucher" number?

I bought Adobe CS4 Creative Suite (Student Edition) years ago and now I had a problem with my computer so i had to reinstall de suite but i have no serial but only a "Gutscheinnummer" (in German) so something like a "voucher" i can change into a serial. How can i now get the serial again?