Depending on which color you dyed it you can use various products. Prell shampoo is excellent at stripping hair color, without having to wash it 500 times. If you completely hate the color you can use Color Oops to remove it. My friend dyed her hair too dark and the salon suggested adding highlights to soften it up. I have also heard of people washing their hair in vinegar to remove excess color. I do not know if that works so I would research it first. You would not want to end up with bad color and smelling like a jar of pickles.
i did the same thing....don't try to fix it yourself it'll just make it worse. go to a professional hair stylist and let them strip out the dark color then recolor it back to the color you want. it takes a few hours because it's a gentle process, I also put a few highlights in my hair during the process which i loved. after you get it fixed your hair will be extremely dry, so you'll need to deep condition it once a week for about a month to help restore the moisture, this you can do on you own at home.
I think it's probably better if you seek professional help. If you want to really fix your hair go to a salon. If it was a permanent hair color there aren't any shampoos that will do the job as fast as I'm sure you want it done. This answer is coming to you from a person with years of home dying experience and many mistakes in my early days.
I have done that many of times the only way you can get that lighter without it turning a orange color you have to buy a blond hair dye but it has to be a ash blond the ash will make it so it does not turn orange,good luck!!
If you try washing it to lighten it it might take a long time. My advice would be to find that shade you used and pick about 5 shades lighter than that. Try it once and if it doesn't work seek professional help. If u can't afford it usually the vo-tech schools do it very cheap since their learning under the guidance of a teacher. A good rule of thumb is the color on the box is always done on stripped out hair so it will never look like ur hair color on u because of ur haircolor.
One and Only Color Fix.. My hair is naturally a 'dirty dish water' brown, and usually is colored by a professional to be a more attractive medium brown with light brown highlights. I have never home colored before, and due to money issues, I used a permanent box color for the first time yesterday. I am starting to have grays that I don't like, so I got a color that is supposed to be a medium brown. SUPPOSED TO, being the keys words here. It turned out looking black! ARGH!! I bought the color fix today, and followed the partial correction instructions, and it did the trick..it is again brown, no weird color..just brown again ( A little darker then when I have it done). My hair is below the shoulder, and I still have enough left to do another application, if I decide to go lighter. The instructions are vague on time to leave it in, so I kept checking, and left it on around 15 minutes. The hair feels good, and the smell is not as terrible as I have read..I simply cut on the exhaust fan in the bathroom before starting. I hope this helps put someone at ease..I was really freaking out about using something at home again, after my 1st at home disaster!