Dell 235O wirelss broadban router-light is off

all other lights on the router are on when powered up (power/LAN/Internet) only the light for the Wireless does not come on-the dell router is hard wired to my modem and connected to my desktop PC through what look like a USB connection and have checked for loose or unplugged cables and wires-------the wrieless has been fine until recently

am wondering if the wireless light only comes on when it is being accessed

could the router itself be faulty? it is about 4 years old

internet is fine to my hard wired pc--