Gray hair problem. Gray hair naturally?

Hi, my age is 28, I have gray hair problem, I started having my gray hair at the age of 25 and where I was having only 10 strands of gray hair to cover that I have applied Garnier color naturals hair dye and continued for 2 years but now most of my hair is turned into gray and from root it is growing as gray. Last one year I stopped applying hair dye and started with henna. Since most of my root of hair is growing gray I am applying every week henna and having severe hair fall as well. I want to stop using henna and would like to grow my hair back from root. Is there any way to reverse gray hair process. Earlier I was also having severe stress but now my stress is also reduced. Is it possible to reverse the gray hair naturally? Kindly recommend me food and natural remedies to   reverse the gray hair process.