If you can't locate or join or a Wi-fi network, or if the signal strength appears weak or low, try the following steps:
- Press the Home button
then the Menu button 
- Touch Settings then Wireless and network and turn 'Wi-Fi' off and then on again
- Verify that you are in range of your wireless router
- Confirm that your wireless router and/or modem are connected to power and turned on
- Check whether other devices (portable computers, for example) are able to connect to the wireless network and access the Internet