How to figure out a Wi-Fi password?

My friend put his Wi-Fi password into my ipod touch so I could be connected to his Wi-Fi. I just got a iphone so now I want the Wi-Fi password on my iphone. He says his mom can't find it anymore. How do I find out what was the password that he used to put into my ipod touch.

You would have to look into the router settings.

You can use wireless key view on a PC that already has the password stored. Only works if that computer has a wireless NIC card installed. Or you can press the reset button and set a new password. Wireless key view does not work on non PC devices.