You might try toggling to a "wired" connection, and then switching back to wireless to see if you can detect your network. If that doesn't work, you can hold down the FF>> button for 12-15 seconds, and that should reset your network settings.
I got a new router and have changed the password, though kept the name of the wireless network the same. I can't seem to find where to change the password though, , have been through settings , network, wireless network, blah, blah, and can't find a place to change it! can anyone help?!