Led lights not working

[Andy2567]

I have a few strings of led lights that only half the string is working. I have checked each bulb and used Both a light keeper pro and a none contact volt pen. I can't seem to find out where the break or bad bulb is.I also under stand that you need to take a bulb from the side that is working out because of the third wire carrying power all the time unless this is done. I can't bring myself to throw out all these strings of leds. Net lights and icicles. I am going out of my mind with this.