Laptop won't detect wireless connection (but does detect others)

How many wired and wireless computers do you have ion the network.
Do you have any wired computer ?
Connect your laptop to the router with the Ethernet cable and try to access Internet. See if the wired connection is working or not.
If the wired connection is working then I think you will need to check the wireless settings of the router and the laptop.

Try following websites

Router setup
How to connect to the wireless network

HI,
I see you set Windows back to defaults as you mentioned and now your Router will not go Wireless.
First Restoring Windows Back to Factory Defaults will not reset your Routers Settings to Defaults together with Windows.
So Most Probably the issue is since you restored windows back to factory defaults you may need to install the Wireless Driver again on the Machine / Computer to make your computers wireless card work again and be able to detect and connect to your Belkin Router.
try a difefernt device that can connect wireless to your Router or maybe a different Laptop to see if the Belkin is working fine wireless.
If any other Laptop will not detect the Belkin then try turning the Wireless Radio ON again in the Router Settings of Belkin.
But I suggest to check all your system drivers if installed for it to be wireless capable again on the issue, Restoring Windows back to Default will not change anything in the Belkin Router. I believe this is a Driver issue on the Wireless card of your Computer.
You mentioned the system does work if plugged in Wired right, check your drivers install every driver that needs to be installed from the Manufacturer Website of your Computer for proper and compatible drivers.
Have a nice day.

If your using a router to get wireless from a DSL connection and your laptop isn't detecting the signal it is most commonly the wireless card in the computer, hence their response. If you can access the router to check what channel it is transmitting on you may be able to change that to resolve the issue. On my cisco router it transmitted on channel 6 by default and my laptops wouldn't detect it, I changed it to transmit on channel 5 and the laptops work fine. I assume they checked if your router was compatible with your computer so I won't go into the type G wireless vs Type B or N wireless. The uninstall/install process they recommended is not hard and shouldn't hurt anything if you do that. On Vista Open Control Panel->System->Device Manager then go down the list of devices to Network Devices and select your wireless adapter and right click, from that drop menu select uninstall and close everything and reboot the computer. When the computer starts up again it will automatically detect the wireless card and reinstall the drivers from the windows system copy. Make sure the wireless device is actually manually turned on before doing any of these steps. Once the device is installed again you should be able to detect the wireless signal from the router they supplied. If not there is one more place to look in the router itself unless you are familiar with router settings I don't recommend you do these though. If you still don't detect the router signal call your supplier back and have them go through the router connections with you and when they say it's your computer you can tell them it works fine with others and you removed and installed the device as they advised and the fault is in their router.

Same Problem I am facing too. I am also having SONY VAIO VGN-CS21GN

download the intel chipset driver

http://www-307.ibm.com/pc/support/site.wss/MIGR-46058.html

you look to be having the software but you need to confirm if its the wright software. make sure that you getting them from the software CD that come with the laptop. if your downloading from the internet make sure that its from the wright manufacture of the your laptop. if your not sure please send me the wright model and brand of your computer i will help you to link you to the site.otherwise your wireless card should work.

try plugging the wireless mouse receiver into a different usb port
reboot your machine
is there a key on the keyboard with a little wireless symbol? if so it is probably in blue and there is fn key that you need to hold down while you press the wireless key to turn on the wireless

i neead wireess lan drivers

You can try this site:
http://www.z-cyber.net/WirelessLAN%20PCMCIA.htm

Your card is actually a BritePort™ Wireless LAN PCMCIA Card 2020, which was marketed by Creative. It's made by Broadxent, which is a British company. Either write to Creative tech support and ask for the driver, or contact Broadxent.

download a program called driver genius (its free) this will scan youre pc and inform you of all the drivers you have or require.if you purchase the program it will find and install them for you.but it solve youre problem.if next time you could mention brand of laptop I could probably tell you the drivers you need or at least the site.