Instructions
Check the light on your wireless networking adapter to make sure it is on. Occasionally, power outages or surges can cause the adapter to turn off. If you do not see a red or green light lit on the adapter unplug the adapter's USB cable from the back of the Xbox 360, wait a few moments and plug it back in. The adapter light should turn on momentarily.
Make sure your router is broadcasting an SSID, or wireless network name. If this function is disabled the adapter will not connect to your network. Read your router instructions for steps on how to enable SSID.
Move your console closer to your network. Put the Xbox 360 in the same room as the wireless router and try connecting to the network again. As a general rule, Microsoft suggests that players place their Xbox 360 where as few obstructions as possible exist between the gaming system and the router.
Move other electronic devices away from the Xbox 360 that could cause a disruption in the wireless signal. These include such objects as other gaming consoles, cordless phones, microwaves and other electronics that use the 2.4-GHz radio frequency band.
Set your wireless network to use a 802.11g or 802.11a connection, which usually experiences less interference from other electronic devices.