ADE won't open to "Library".

I have been using ADE for some time. I recently downloaded an EPUB file, and commenced reading it.

Next day when I tried to open ADE (double clicked on icon), it only opened to a blank page, with "File, Edit, Reading & Help" in the menu bar.

However, the downloaded book was not there, and when attempting to "Add to Library", the Fulfilling" dialog box would open, but no book appeared.