Wireless Home Network Not detected!

Hi, I have a Toshiba Satellite L655-149 laptop.

There seems to be a problem with the wifi. Normally, when the ethernet cable is not connected it would show the available wireless networks (like any other laptop).

But now it does not detect any wireless networks including my home network and I am sitting right beside the router.
I tried pressing Fn+F8(buttons to enable or disable the wifi) but that function isnt working anymore.
Is there any other way to turn on the wifi?..or is it something wrong with the driver and the wireless LAN card in my laptop?
Thank You

Yeah when the ethernet cable is not connected there is a symbol of a computer with a red X on it at the bottom right part of the screen. But when I click it, it displays No connections are available. So it does not detect my Home wireless network.
Please tell me how to go to network center and change the adapter settings.
I went to Device Manager and clicked on Network adapters. It shows just something called Fast Ethernet Controller. Nothing concerning wireless connections. Could that be because the wireless LAN driver isnt installed?

Yes only the Fast Ethernet Controller was listed in Device manager.
When I searched Network in control panel i got network and sharing Center. I went to that and I clicked on change adapter settings but I could only find Local Area Connection. No wireless adapters were displayed.

I ran the PC diagnostic tool. Under the Basic Information tab, for Network it just displays:
Atheros AR8152/8158 PCI-E Fast Ethernet Controller(NDIS 6.20) version=1.0.2.43 MAC Address=00:26:6C:78:C6:C1

Nothing on the wireless adapter.