hi there. i will be happy to help
is the wifi icon still on the bottom right near the clock?
if it is you should be able to just click on it and select your network and put the passkey back in.
if it is not there
right click on the windows logo on the bottom left
select device manager
find it in the list and right click on it
then reboot the computer and hopefully it will reinstall itself correctly
then follow the first instructions to get it to connect to the router.
if none of that works you probably need a new driver for it. I would need the exact model number to find it for you on the asus website.
i can also log in remotely to fix it for you if you can connect the laptop to the router with an ethernet cable and get the internet that way while i work on it. there is an additional charge for that so i will just put it up as an option for you if you want to try my instructions yourself first.