How to restore my library items?

I created an "Adobe Digital Editions" account and subsequently purchased a few ebooks. The seller sent me links, which when clicked added the ebooks to my ADE account.

I then installed "Adobe Digital Editions" on my PC and ipad. After authorizing these devices, my ebooks were automatically downloaded. Everything worked fine and I could access my ebooks without any problems.

One day something happened and I couldn't open my ebooks on my PC any longer. To try fix this, I thought I could remove everything from my PC and add it back. So I removed the ebooks from my library (right click on each ebook, then "remove from library"), I uninstalled ADE and deleted the content folders under "mydocuments". I then tried to unauthorize my PC but got an error saying "unable to erase authorization please try after some time"

How can I restore my ebooks on my PC?