Apparently seems like your W-LAN card is either disabled from your network connections or may be there is some hard switch which turned off. All you need to go open network and sharing center then click view network connection to make sure that you Wireless connection is not disabled in any case it should have to be enabled.
Other way is to check on your keyboard from top F1 to F12 keys if you can see a Antenna sign on any of key then press that key by pressing Fn key together.
If the problem still persist then I would recommend you to go on your manufacturer`s website to download the latest driver and update your driver. Good Luck