Passport Essential works with XP and now not with Win8

WD External Drives External Drives for PC
2

http://wdc.custhelp.com/app/answers/detail/search/1/a_id/5419

Go to device manager and chesck if there is a yellow triangle listed on universal serial bus controller. If there is download ses driver. Also if you are using a laptop make sure that the laptops power adapter is directly connected to a wall outlet.