The front-facing camera on your Kindle Fire HD is not taking pictures or you aren't seeing an image when you use the camera.
Before taking a picture with the front-facing camera, remove any obstructions from the lens and make sure you have enough light, because the camera does not have a flash. If you are still having trouble, restart your Kindle Fire.
Press and hold the Power button for 40 seconds or until the device restarts automatically. If your device restarts automatically before 40 seconds has passed, release the Power button. If your device does not automatically restart after 40 seconds, press the Power button to turn it on.