Is the store that you purchased the ebook from still in business? If you do not have the ACSM or the ebook, you will need to go back to them and see if they can give you a new copy. Adobe Digital Editions does not track your purchases for you.
Got it, I looked for an old backup I had, fortunately I had it saved in there. I opened with the new version of Digital Editions and it worked, of course it asked for my userid & password (the one I used for login in into adobe.com) to be able to open the file.