Instructions
Check the physical "WLAN" switch on the left side of the PSP unit; make sure the switch is set to the "On" position. If the switch is in the "Off" position, switch it to the "On" position and attempt to connect to a wireless network.
Disconnect from any networks your PSP is currently connected to. Select the network to which you want to connect from the list of available wireless network connections. Make sure that all the network configurations in your network settings are correct.
Unplug the wireless router that provides your wireless network and let the router sit without power for 20 seconds. Plug the power back into the device and wait for it to reboot before attempting to reconnect to the network with your PSP. If you cannot access the wireless router, or if you are using a public wireless network, skip this step.
Check to make sure the wireless network is not encrypted. If the network is encrypted, re-enter the encryption key on your PSP and attempt to re-establish a connection.