Method 1: Try connecting the Kindle Fire device into a different port and check if it is detected. I would suggest you to disconnect the Kindle Fire device from the computer and then try connecting it to another port and check if it is detected by the computer.
Method 2: Try Restarting the Kindle device and the computer and the reconnect the device. Try restarting both the computer and the Kindle Fire device and then reconnect the device to check if the device is detected by the computer.
Method 3: Run the Hardware Troubleshooter. The Hardware Troubleshooter is an automated tool which will check the hardware connected to the computer for any known issues with it and provides the details and on how to fix them. Follow these steps and run the troubleshooter.
Press “Windows Logo” + “W” keys from the keyboard.
Type “Troubleshooting” in the search bar and press “Enter”.
In the “Troubleshooting” window, click on “View All” on the left pane.
Click on “Advanced” and then click on “Run as Administrator”.
Click “Next” and follow the on-screen instructions to complete the troubleshooting process.
Since the device is completely compatible with Windows 8, let’s check the Windows updates for any latest drivers available for the device.
Method 4: Check the Windows updates for any latest driver updates. After running the troubleshooter, check in Windows updates if any driver updates are available. If so, install the same and check if it helps.
Type “Updates” in the search bar and click on “Install optional updates” from the left pane.
From the “Windows Update” window, click on “Check for Updates” on the top left corner to receive a fresh list of updates and install all the updates listed there.
For more information, check this link for the troubleshooting steps for the common issues with the Kindle Fire. Please select the Kindle Fire device that you have and then check the article “Connecting Via USB”.