acsm files wont open, epubs wont open, ADE wont unauthorize

I've purchased a book from Google Play, I downloaded the acsm file and tried to open it. ADE opens but that's it - nothing else happens. The book is not in my ADE  library and no error message appears.

So I tried to open directly from ADE using the File menu. selected the acsm file in my download folder and again - nothing, no error message, no book no nothing.

Whilst my library on ADE is still populated with titles none of them will open - ADE doesn't recognise them

Ok I think, I'll de-authorize and reauthorize. I can't. I click on 'Erase Authorization' enter userdID and password and get the message 'Adobe can't unauthorize at this time please try again later' (or words to that effect)

So I've uninstalled ADE, downloaded from the ADE website again and reinstalled. Still nothing

This is also happening with library books I've downloaded via Overdrive - I'll download the acsm file but then nothing, no book, no error message, nothing.

I've not had this problem before - bought books from Kobo and from Google Play, and borrowed via Overdrive with no issues. In fact I last borrowed books from the library 3 weeks ago (3rd March) with no problem.

I'm using ADE 4.5.6 on Windows 10

Please help me!