Is the the power adapter for the external hard drive plugged in?
My brand new Asus G75 laptop won't recognize my Western Digital 1TB external hard drive.
It works in my friend's almost identical laptop, and my laptop is correctly recognizing other usb inputs. The hard drive spins when plugged in, but the led on the exterior of the drive doesn't come on. I'm pretty sure it isn't showing up in device manager or disk management.
I've also tried all the ports.
I think I read somewhere that some driver updates can screw up the usb's, but the problem only comes up with this hard drive.
Here are where I've looked for it: http://imgur.com/PR6oU