First, disconnect Kindle from computer and try plugging it back in using a different USB port. You can also try using a different micro USB cable, if available. If it is still not working, follow these next steps:
1. Restart Kindle by pressing Home > Menu > Settings > Menu and select Restart. 2. Connect the Kindle to a USB port on the back of your computer. 3. Restart your computer with the Kindle connected to it.
If these steps do not resolve the issue, you can reset your Kindle. Unplug your Kindle from the outlet or computer, slide and hold power button for 15 seconds, and wait for 5-10 minutes.