usb power from sockets but no data tranfer medion laptop?

i was using a web cam , as i pluged it in the medion laptop intsantly powered off i started it up now no usb device will work there is power from the sockets windows reports no fault but its as if nothing is pluged in. there are some small black what look to be resistors solded across each of the centre tracks from each usb socket no motherboard and i am wondring if these are some sort of protection an may have been damaged.?