I was able to read all of my previously downloaded e-books on my Sony e-reader until I tried to correct a mismatch between the e-mail address shown as my Adobe ID on the reader software opening page and my e-mail ID registered with Adobe. I de-authorised the computer and e-reader and re-authorised them with the correct e-mail ID. Now I cannot open any book as it says it is DRM protected. HELP
In context of what you have written in your topic you may want to consider going to the Digitial Editions user forum and ask there.
https://forums.adobe.com/community/adobe_digital_editions
Be well...