You _might_ find it if you log on to your Adobe Account.
When you buy any Adobe software that you paid hundreds for, it's important you register it. That way the serial number is saved online under your account.
Otherwise call Customer Support explain the situation and be ready to show proof of purchase.
Failing that, you'll have to sift through everything. It might be in the DVD case or on a card in the package.
Since you bought it from the university bookstore, in a box, my first question would be, "did you Register it with Adobe?" Registering your software is not to be confused with Activating it (since CS), but is a separate operation.
If so, then if you log onto Adobe.com with your Adobe ID (provided that you used that one to Register), go to My Products (think that's the correct syntax), and look for your S/N there. That was Trevor's suggestion.
If you did not Register with Adobe (since you did not buy directly from the Adobe Store), Gener7's suggestion to contact Adobe Customer Support directly, is about the only way to handle things - also, when you get that S/N, that the advice to archive it in a safe place. That is advice that most people can benefit from.
I will also Edit the title of your post, to more accurately reflect the problem that you are facing. That might help others, if they have the same issue, and Search the forum. I hope that you do not mind.