Hi there! My name is*****'m sorry that you are having this problem. I will do my best to help you with it. This problem and many others are often the result of a "glitch" in the software. Luckily, it is easily fixed.
Please do the following:
Remove the charger from the Kindle and hold the power button or switch in the OFF position for about 20 seconds.
Release the button or switch, then connect the charger and try to turn on the Kindle.
If this doesn't work, please repeat the steps and this time hold the power button or switch in the off position for a full 40 seconds. This should reset the Kindle to factory defaults. You will know that it successfully reset to factory defaults, if it reset the Kindle back to the way it was when you took it out of the box. Did it do that? If not, please try it again, being sure to hold the power button for a FULL 40 seconds. If it did require you to set it up again, then the factory reset was successful.
If you do have to reset it to factory defaults, you don't have to be concerned about losing your books. The books that you have purchased from your Kindle will continue to be available at the Amazon website under My CONTENT.
After resetting the Kindle, just make sure when you set it back up that you use the same Amazon email address and password ***** you are currently using. After setting up the Kindle, please login to your account at Amazon.com. Select YOUR ACCOUNT. From the drop down menu that appears, please select MANAGE YOUR DEVICES AND CONTENT. On the page that appears next, you will see a CONTENT Tab and a DEVICES Tab. On the CONTENT tab you will see all of your Kindle book purchases. You can sort them by title, author or purchase date. Please locate the book that you want to download to your Kindle, select it by checking it and then click on the ACTIONS column. Choose deliver as the action. Select your device from the Device list. If you have more than one Kindle, make sure that you choose the Kindle that you are actively using. Don't select the Kindle Cloud reader unless you have downloaded the Kindle Cloud Reader APP to a computer or device other than your Kindle and wish to read it there.
Please give this a try and let me know how it works for you. If this solves the problem., would you mind taking a moment to rate my service? I'd really appreciate it! If you need more help, please tell me exact model of your Kindle. If you're not sure, please look for a serial number. If you can't find it on the Kindle, you can find it on the Manage Your Kindle page of your Amazon account (in the Manage Your Devices section).