Try re-installing your laptop's wireless driver, you can get it from your laptop maker's website.
If still no joy, look in Device Manager to see if the wireless adapter is actually listed there without any errors.
If it isn't listed at all, and no errors shown, the wireless adapter may have broken.
You can workaround that by buying a USB Wireless Adapter, but do not plug it in until after you begin installing it's software from the included CD. You will see a message on screen telling you when you can plug it in.