I'm sorry about the issue. What's the model of your kindle?
Please try a possible fix below:
1. Disconnect the power cord(s) from the internet / wireless modem/router device(s) for a few minutes, then reconnect.
2. Press and hold the Power On /Off button on the kindle for about 45 seconds, then turn it back on and check.
3. If that does not work, go to Wi-Fi/wireless setting on the kindle, then select your wireless network name, then select the Forget... option if shown, and confirm. Then select your wireless network name again, and see if you can connect.
Please reply at the box below to continue troubleshooting. Thank you.