If your hair died, then that is the end of that! Not sure what you mean by that. Are you saying you killed your hair somehow?? It is not a living thing, so you can't kill it.
If you made your hair a different colour [called "tinting" in the profession], then that is how it will be. Since you put the chemical colour particles in your hair, they should stay there. Sometimes, when the hair is exposed to a variety of other chemicals, like shampoo or sunlight, these particles will come out. Not all, but only some, and you might get strange off-colours.
If you made a mistake [sounds like you did], then you need to fix it. There might be ways to remove those artificial colour particles -- depending on what you used. You never said, and we can't see it very well from here. Go to a professional hair colourist who does repair work and have a consultation. There might be something they can do. Some colour products are just impossible to remove, so you need to know.
The good thing is that hair continues to grow, and it will be like it was in no time at all. You cannot change the way the hair is formed under the skin. When the hair grows out, it will be as it was. The ends will eventually have to be cut off to remove all these darker bits, and only time can do that. Or this might be a good time to play around with some really short hair styles!! It's only hair -- it will grow on you!