iPhone 4 keep searching for wifi but not getting result

I was able to use it yesterday, and I was trying to backup an app data throught wifi connection. After couple hours, the wifi connection was dropped, and it just keep saying searching for network but nothing pops up at all.

I've tried rebooting the device, resetting network under general, turning on and off airplane mode, but it's still searching. My friend's ipod touch is able to find the internets that's available from and around our house, but mine cannot detect anything.

I've been told to restore the phone, but I've heard things about iOS 6 has software issue that could cause a hardware problem.

Can someone help, please?

Thanks.