How Can I Reactivate My License for Previously Purchased eBooks on Adobe Reader

I need help.  A year ago I purchased several eBooks using Adobe Reader onto my laptop, and they uploaded perfectly.  I had since upgrade the Windows version (to Windows 8.1) and when I try to open any of these titles in my Adobe Reader library, I get and error message that my computer is not licensed for the eBook.  If I go back to the original email receipt to redownload the eBook, I get a similar message.  I only downloaded these titles once, so how can I access them again.  I have paid over $100 for these titles, and I don't want to repurchase them.  I would appreciate some guidance.

Thank you.

-John