My hunter fan has been working great for years. All of a sudden the light won't burn took it apart tested it and there is not any power on the white wire / black stripe can't figure out why is it the square box up top on the fan part help please

Your white wire is the neutral and will show no power if the fixture is not operating. Test between the black striped white and the ground to see if power is reaching the unit, then repeat testing between black and white, still get the same results? Back to you

Okay,

By code, 200.6(A)(3), a wire smaller than 6 AWG that has three white stripes on any color other than green is a "Neutral" wire. According to 200.6(A)(7), fixture wires must comply with the identifying characteristics of 200.6.

Now what all that means is that the white/black wire should be a Neutral wire and will not have voltage on the wire until the circuit is in use.

I need you to define what you mean by the following:

"Taken apart" and "Tested".

What did you take apart and how did you make your tests.

The most common failure with a light package not working is the pull switch? Does your light have a pull switch or is it controlled by a remote control?