find the drive in device manager and delete it. It will ask if you want to delete the drivers - answer yes.
Unplug the drive from the usb port and shut down the pc.
Power the pc back up after a minute and when windows is done loading insert the drive into a usb port which should reload the drivers.
These canvio drives are not very reliable from my experience with them. If you can still return it, I would.
Also you should remember that important data should never be kept on just 1 device. Everything breaks and having more than 1 copy is essential if you want to survive it. I tell people that external drives should be used for copies of files only, never for your only copy.