My name is***** am sorry to hear that you are having this issue.
I will be glad to assist you with this.
This may be caused by a glitch in the firmware and can be resolved by a forced reboot, then your kindle will work normally again. Slide or press and hold the power switch for 40 seconds, then release. Then check if you can shop the store. If that fails try checking the registration on the kindle>
let me know if that works please.
Did that work for you?