When I had to go back to an earlier date I had to reinstall my program. The error message is because it needs the drive from the download to be able to read the info. I also freaked out at not finding my EQ files but they were all there. I just had to find them in my hard drive. Anything you created only the original file survives the reset.
I don't know what kind of pc you have but I have an HP. I found all my originals in my C drive.