I made the mistake of installing something called Internet Download Manger. It took over my computer and I hated it. So I uninstalled it using Revo Uninstaller. That was a BIG MISTAKE. That's the first time I have ever had a problem using Revo Uninstaller. After I used it - I opened Calibre and my books were ALL GONE! Well, it had completely also wiped out my Roboform database but that wasn't as bad as losing all my books!
I tried using the restore feature from Revo, but since I had never looked at that before, the restore went to my Recycle Bin and was not stored on my Computer! Oy! I used it anyway in hopes that something would work but it didn't. I tried Windows Restore. Nope.
Finally - I downloaded a program called
7-Data Recovery Suite (since I was Nsane & Down
and Lo & Behold it WORKED! It found a folder called
Lost Files and in it were all my books! I just had to go in there and check the books one by one and not all the other files it found. I then saved them to a USB drive and then dropped them into my Calibre Folder and updated it.
I did get some errors since my Kindle key has changed! But that's better than all the books I thought I had lost.
7-Data Recovery Suite was extremely easy to use.