The 120GB drive blue light does not come on when plugged into USB anymore. is it toast?

First try hooking up to a seperate machine. If it works on another machine than your computer may have a problem with the driver.

If that doesn't work, try disassembling the case and removing the drive. Then hook the drive up to a desktop computer as a slave drive. If this works then your interface to your drive is bad. You can find external cases online at a store such as newegg.

Lots of things could be wrong here, the drive could have gone bad, your computer USB port, the USB cable or the power supply. Before you toss it out, I would suggest you swap out the cable first or test it on something else, if you get any light that means the power supply is ok. You next step would be to swap out the Drive with a known good one, before you can do that you would need to open it up. Remember if it`s a my book you can only use Western Digital drives in there. Good luck.