Moved from the Adobe Captivate forum.
That product code is not the serial number needed to install Lightroom. When you first purchased the teacher edition you had to validate that you qualified for the discount. Then you were sent an e-mail containing your serial number. That serial number is very important, and something that you should have stored in a safe place. You can log into your Adobe account and see if the serial number is recorded. If not, then I suspect you won't be able to reinstall. Adobe no longer supports Lightroom 4, any edition. So it's up to you to have your serial number. For your information, that serial number will have six groups of four numbers, and first four will be 1160.