How do you enable wireless internet on a PC laptop with Windows Vista as the operating system?

I have two laptops, one is able to get internet over my WPA2 secure wireless network; however, my Sony Vaio cannot sense any networks and it says the wireless network capability is turned off when I try to troubleshoot the connection issue (or lack thereof). My problem doesn't concern my router because I... show more I have two laptops, one is able to get internet over my WPA2 secure wireless network; however, my Sony Vaio cannot sense any networks and it says the wireless network capability is turned off when I try to troubleshoot the connection issue (or lack thereof).

My problem doesn't concern my router because I know I am able to access the router via 192.168.1.1 and my wireless internet with my internet browser.

I know there is a On/Off WiFi toggle switch on the front of the laptop and oddly it's switched in the 'On' position, (I've made sure of this).

What could be preventing my laptop from sensing my home WiFi network? Please let me know how I would be able to turn on the wireless internet capability on my Windows Vista laptop. I know it works on my home network, it worked last week but suddenly quit after most likely being used by my little brother! Thank you :-)
-Mike