I have tried to do natural horsemanship training with my horse because she is not trusting at all but it seems like the more I do the natural horsemanship stuff with her the worse she gets what should I do? About your horse getting more and more untrusting. First off let's take out the obvious and that is there any physical problems that your horse may have? Arthritis, sore teeth or mouth, very sensitive skin, hoof problem? If your horse has been experiencing some sort of pain that has been getting worse through the years she can just be leary of everything because she is in constant pain. She may do well when doing barrels because the pain is increased and she has learned already that the sooner she gets done running them the sooner the extra pain goes away.
If you know that she isn't experiencing pain then it could be that people have been too rough and demanding on her even if their intentions where to be friendly. Because in her eyes she has been controlled and not allowed relax and understand what the human is asking she gets frustrated and feels unconfident. Thus getting more and more scared over things.
I suggest you just pet her each time you see here for at least 10 minutes at a time or until her eyes have a sullen or very relaxed look. Whichever takes longer. Once she trusts you with petting then you can start asking for more.