Pam, Sounds like you must have done a reset between the time you stored your books on the keysoft disk. They are gone.
You need to store anything you wish to keep on the flash disk. Doing a reset will cause you to loose anything you saved to the keysoft disk. It's really for system use only and you should never store anything there. Just use the flash disk and create a "books" or "my books" folder on the flash disk and keep your books there. You should never loose any of them if you do this, even if you do resets. Don
