Instructions
Reboot your network modem and wireless router. Unplug the power cables for each device and leave them unplugged for 30 seconds. Plug each power cable back into its respective device and let the devices boot up and begin operating. Once each device is properly rebooted, try to connect to the wireless network connection on your PlayStation 3 again.
Verify that the wireless network capabilities of your PlayStation 3 are enabled. Open the "Settings" menu on the console itself (not on your computer) and select "Network Settings." Open the "Internet Connection" window. The option labeled "Enabled" should be selected. If it is not, highlight the word "Enabled" using your controller and press "X." Attempt to connect to the wireless network with your PS3 again.
Check the status of your Ethernet cables. Even though the PlayStation 3 is connecting to your network without wires, the modem and the router must still be connected using an Ethernet cable. An Ethernet cable should be inserted into the plug labeled "Out" on the modem and "In" on the router. If the cable is hooked up incorrectly the wireless network cannot be created properly.