My wireless contoller wont connect

the xbox site has a good list of solutions: http://support.xbox.com/en-us/pages/xbox-360/troubleshoot/kb/error-your-network-does-not-have-sufficient-mtu-setting.aspx?kbid=979104
From that list, here's a couple simple things to try:
If it has worked before, try rebooting your home router (or unplug it from the outlet, wait 10-15 seconds, and plug back in).
If it has not worked before, and it is wireless, it may be a weak or wireless signal. Try moving any cordless phones away from the xbox or home router, or moving your router to a different location, even a couple feet away.

There is a sync button next to the Play and Charge port on the controller, all you have to do is press both the sync button on the Xbox and the controller and it should connect. On the nonslim Xbox 360's the sync button is right next to the infared sensor and the memory card slots. On the slim Xbox 360 the sync button will be right next to the usb ports on the front of the Xbox 360 console. When you successfully start the sync the led's for the controller's and console's lights will spin and be ready for you to press the sync button on the other device.
(PS, you have to have both the console and the controller on for this to work; PPS, By controller on I mean having it searching)

If you press the the small white sink button on your
console and the the lights don't go around in a circle
then the RF / Power button board is defective .
The name of the part goes by the name R.O.L.

They are cheap and easy to install ( plug and play)

Rob

if your trying to use the controller to play games on your pc you cant unless u buy the microsoft adapter wireless gaming adapter for your computer, if your trying to just charge it, you just connect the charge cable to your usb drive and windows will automaticly find the drivers.

Try to remove the hard drive and play a game. This will tell you if it is the system or the hard drive itself.

Have you ever synced one of these controllers before?

Hold the controller in your hand as if you were playing a game. Next flip the controller up so that the buttons on it, are facing you.

There is a small white button that you will see. Power your xbox up and after you get to your main menu press the sync button located about 2 inches to the left of your main power button on your console.

Press the described button on the console and then the described button on your controller. The two should sync together perfectly fine.

well you might want to press the little button by the battery pack at the top and the little one on the 360

If you're using an HDMI connection between the Xbox 360 and the TV, it might be that. When using HDMI, the Xbox won't boot up until it knows what the TV is capable of displaying. Although the controller will turn the console on, it won't sync with the console -- and it's not a controller or console problem, but just a symptom of the fact that the Xbox won't get to the point where controllers will sync until it can properly communicate with the TV. I'd recommend turning off the TV and the Xbox, disconnecting the HDMI cable and re-connecting it after making sure the contacts are clean. Then turn the Xbox back on first; you'll likely to see the same behavior. Finally, turn the TV back on. With it being switched back into HDMI mode, it just might "kick-start" the Xbox into a good communication link across HDMI. Hope that helps.

Have you tried resyncing your xbox and controllers? On the controller, press the little circle button on the top of the controller, between the bumpers. On the 360, there's a small circle button, about half inch wide, next to the memory card ports. Press that as well.

Console-to-Console Connection: Wireless Some Xbox games offer console-to-console, or system-link, play, in which two or more players (depending on the game) can wirelessly network their consoles for multiplayer use. Console-to-console wireless networks are also known as ad-hoc networks. In ad-hoc networks, a wireless adapter on one device connects directly to a wireless adapter on another device. An Internet connection isn't shared with this type of network, and the console-to-console connection is typically temporary. For console-to-console play, you need: Two Xbox 360 consoles. Two Xbox 360 Wireless Networking Adapters. An Xbox 360 game that supports system link play. To wirelessly connect your console to another console: Attach an Xbox 360 Wireless Networking Adapter to the back of each console as described in Use Your Xbox 360 Wireless Networking Adapter. On each console, go to the System area to enter your network settings. (They will be the same for each console.) If all settings are correct, exit the System area. The consoles should now be wirelessly connected to each other.