First off...make sure your laptop, if it has one, a button for wireless on/off is set to on and not off. Does it even show a wireless connection icon in the system tray? Or in network connection under control panel does it show an X'ed out WiFi connection?
Second easy check is go to where the "X" is on your network connection in the system tray and see if it shows any "available networks in range" to see if it's even attempting to connect.
From here...we can go on into more detail for you.