|Look in Device Manager:|
Start >> Control Panel >> Device Manager
If the wireless device is not listed under "Network adapters", & there are no error symbols showing, it may mean the wireless adapter itself is faulty. This is a common problem on HP & Compaq laptops.
If it's still under warranty, Compaq will fix it free. Otherwise you will have to pay them, and it will be much cheaper just to buy a USB wireless adapter and use that instead.