From time to time your Apple TV may freeze, or an app may refuse to perform properly. When this happens, try restarting the Apple TV. This is a quick fix that takes only a few seconds and can solve many problems. If restarting doesn't work, try resetting the Apple TV. As a final option, you can restore the Apple TV to its factory settings.
Restarting an Apple TV
Press the Menu button on the Apple TV remote until you get to the Home screen. Select Settings.
Select General. Scroll to the bottom of the General options.
Select Restart to restart the Apple TV. After several seconds the Apple logo appears on the TV screen and then the Home page begins to load.
Resetting or Restoring an Apple TV
To reset or restore an Apple TV, select General from the Settings screen, scroll to the bottom and select Reset. On the next screen, there are two options.
Select Reset All Settings to reset all of the Apple TV's settings, including configuration options and account details for iTunes and other apps. When the Apple TV starts again, you will need to enter all of this information again.
To restore the Apple TV to its factory settings, click the Restore option. During the restore process, the Apple TV will also download and install the latest software. It will then guide you through the setup process, just as it did when you first plugged it in.