Hello. My name is Michael. I can help you with your question.
What I suggest is a full reset. This will wipe all data from the Kindle, but it will sync again when you set it up and enter your account info again. To do this, Turn the kindle off, then slide or press the power button/switch for a full 20 seconds. When it restarts at 20 seconds, it will take a while to start up. When it does, it will take you to the setup screen.