Things to try:
Try all this in the SAME ROOM as your wireless Router/Gateway device.
1) Turn notebook OFF (not Standby or Hibernate), then unhook Power brick from the wall for two minutes.
2) Turn notebook back ON using Power brick.
3) If wi-fi still fails, go into DEVICE MANAGER and find the network device and REMOVE IT, then right-click to recheck the hardware.
4) right-click the network icon in lower-right of desktop and run the TROUBLESHOOTER
5) If all previous fails, go to the laptop support site, find the proper drivers and reinstall.