cannot open a ebook after reinstalling adobe digital

I did exactly the same. Did you manage to fix it?

Unfortunately that is one of the more vicious traps that Adobe leaves for unspsecting users.

Basically, authorization without ID is a very bad idea, convenient as it seems at the time.

There are warnings about it as you make the authorization and again as you replace it, but they are not nearly strong enough.

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There is one possibility that might just work ~ though I'm afraid probably not.

When you authorize 'without ID', you are actually authorizing with a very limited implict/anonymous ID.

When you first open a book, the book gets locked to the current authorized ID.

Try deauthorizing the mac from your real ID (cmd-shift-D), restarting ADE, and authorizing again without ID.

If you are lucky, it will use the same implicit/anonymous ID as before, and you will then be able to read the book.

If so, you may be able to DRM strip it.  Free epubee works on Windows, and they point at a professional program for Mac (see http://epubee.com/)

Don't forget to reauthorize with your real ID again before you go any further.

The whole thing may not be worth your while for just one book, just learn from experience.  Horrible, horrible Adobe ADEPT DRM implementation ....