The Solution when Fingerprint sensors Not Working,

Fingerprint sensors need to be cleaned on a regular basis, so that the performance of the sensor can be fixed up. To clean the sensor should not be with a cloth, tissue or other types of cleaners. To clean use masking tape, stick to the glass surface of the sensor and back off. Do it until the glass surface of the sensor clean. Or if no tape is quite wet your finger with a little water, then rub your finger to the glass surface of the sensor to dry and clean

The things to note:

1. Do not use glass cleaner to clean the glass sensor.
2. Do not use liquid cleaners that contain alcohol.
3. Keep the sensor from water and direct sunlight.
4. Do not clean the glass sensor with rough objects such as paper towels.
5. Do not scratch the surface of the sensor with anything such as your nails.

Problems that may arise in the sensor, if the sleep mode is enabled on your computer, it will probably make the sensor is not active when needed.
Solution:
Disconnect the sensor from the USB port and plug it in again. This way you do when the sensor light is flashing when a finger is placed on it. This indicates the sensor is not installed properly and can not be used.