Reinstalled - still not working

I reinstalled ADE because that is what a Google search told me to do if it was saying that it was unauthorized....even though it was authorized.....when trying to add a book I had downloaded from my public library.

After installation - still won't let me add the book to then put it on my nook. Tried to deauthorize the computer because it is authorized with an old email address and it won't let me do that either. Someone help!