Download and install the latest Chipset and Wireless
drivers from the ASUS site:
ASUSTeK Computer Inc. -Support- Drivers and Download G73JH
You can see what hardware you have in Device Manager.
Winkey+R, type
devmgmt.msc and press
Enter or click on
GO to get there.
Also, is there a switch on the computer that turns the Wireless on and off? If so, make sure it's on.
Several other threads I've found with this laptop and similar problems were resolved by restoring the computer to it's factory installed state. Painful but sometimes that is the only viable resolution.
If you chose to go this route, make sure you backup your data first (anything you don't want to lose).
See the Users Manual on page 18 for instructions on how to do this. It's at the bottom of the page at the link above.