How could you connect to a wireless network but your computer does not detect it?

I have a windows vista and windows 7 on my laptop and for some reason it does not detect wireless networks. I already have a wireless network set up from previous time but it does not show any wireless networks on the computer.


Its like when you click the icon currently connected to which is after the battery icon and before the volume icon no networks are shown. How do i solve this problem?How could you connect to a wireless network but your computer does not detect it?
Try turning off/on the router and try to connect again. If not try manually entering in the router info such as the ssid and router ip address....click the wireless network icon%26gt;connect or disconnect%26gt;setup a wireless connection or network see if that detects it. Also check that your wireless card/dongle is working properly.