Dell XPS can't detect usb drives, pendrive, extenal hdd, etc.

hi ive just formatted my friend's XPS 15 (L502x) (clean installation), but however the laptop is unable to detect any usb drives.

and i went to the website to search for drivers, and theres not much driver available.
http://www.dell.com/support/drivers/us/en/...viceTag/BCKC0Q1


can anyone help me