Authorization Issue Vendor ID

I recently had to reset my computer. I redownloaded ADE today and tried to reopen my textbook. It will not open for me. It asks for authorization, but does not give me the option of changing the Vendor ID. The drop-down menu is grayed out and unclickable. I have input my adobe ID, but I don't think it will work without changing the Vendor ID because I bought this textbook through my campus store. Help?? I have a quiz to complete TODAY!