I hav a Toshiba 1 TB external HDD. It was working fyn till today. Now it is not showing in My Computer or Disk Management. It does make the sound when I connect or disconnect it from the laptop. and the HDD light remains on.
Go under the Device Manager and uninstall all the USB Controllers then reboot your PC don't connect the 1 TB just yet. Make sure nothing is connect to those ports like a keyboard or mouse otherwise they'll lockup. Once rebooted Windows will rebuild the table for USB Controllers. Now you should be all set. Unless you have some sort of conflict with IRQ or Registry setting. There is a free app called USBDVIEW what you would do is disconnect from all non-disconnected USB devices that are stored on the PC these settings can cause all sort of issues.
I am experiencing the exact same thing. I followed your steps, tipstir, but it only found drivers and installed it as "mini radio". I cannot get windows 8 to recognize the Toshiba Canvio dwc130. Please help! Is there a driver I can download and manually set when asked for driver update?