Dark hair commonly turns orange when it is dyed too many shades lighter than its initial color. This can also happen when bleach is not left in hair long enough.
When you dye hair outside of a salon, the new hair color should be within two shades of the natural color. If a drastically darker or lighter color is chosen, it could have catastrophic and difficult-to-fix results. When someone with dark hair tries to lighten it to blond, the hair will often turn orange unless the job is done professionally.
To fix this problem, bleach the hair until most of the orange is gone. Then, toner will need to be applied to correct the shade.