The Kindle is a very user friendly device. While you shouldn't encounter many problems with it, the unexpected sometimes happens. Fortunately, troubleshooting the Kindle is straightforward and easy for most issues. You should be able to have an unresponsive Kindle back to normal within minutes.
Unplug the Kindle from the computer or power adaptor.
Slide the power switch and let it go. The power LED should glow green for a couple of seconds.
Turn off the Kindle by sliding the power switch and holding it until the screen goes blank. After about five seconds, the LED will blink green several times before turning the screen off.
Turn the Kindle back on by sliding the on/off switch and releasing it.
If the Kindle is still not responding, slide and hold the power button for 15 seconds to force the Kindle into a hard reset.
If the Kindle does not respond to a hard reset, charge the Kindle and give it another try.
Give the Kindle some external power by plugging it into a wall outlet.
Charge the Kindle for about 2 minutes. Make sure the indicator light shows that the Kindle is charging. If you don't see an indication that it's charging, adjust the connection until it begins charging.
Unplug the power adaptor and see if the Kindle responds. If the Kindle is still not responding, force a reset by sliding the power switch and holding it for 15 seconds.
While the Kindle can go extended periods of time without being recharged, try to avoid draining the battery completely between charges to avoid possible unresponsiveness due to low battery. Software updates should be delivered to your Kindle automatically, but you can always make sure you are running the latest version by going into the Kindle's settings and comparing the version number you see there to the Kindle software update site at Amazon.com. You can find instructions for manually updating your Kindle there. If all else fails, make use of Amazon's excellent customer service.
Don't try anything that might cause damage to your Kindle or void the warranty.