To me it would seem that the flash utility to reinitialize the device would require it to run on the healthy drive such as hard drive and then address the Sandisk device at a lower hardware level on he USB bus since if you cant see this device in windows then there is no drag and copy feature to get the files there.
Btw is the USB port on this device free of dust, dirt, corrosion or damage, and have you tried using a different USB cable or port to connect to it?