You just couldn't help yourself when you saw the bottle of black hair dye. Now your hair has a deep black colour, but you really miss the old brown tones of your natural hair colour. If you're worried that you can't change your hair back, don't be. It's not the easiest thing in the world to dye hair from black to brown, but it can be done and done without professional help.
Mix together the water and lemon juice and pour the mixture into a spray bottle. Wash your hair with a shampoo specially treated for dandruff. This shampoo will start stripping the original dye from your hair. Then apply the lemon juice mixture for 5 minutes and rinse out.
Apply a leave-in conditioner when you're finished washing your hair and make sure it's evenly distributed through your hair. Your hair can get dry and harsh from the shampoo and lemon juice, but the conditioner will help strengthen it and keep it looking healthy.
Purchase a hair dye removal kit from your drugstore or pharmacy. This contains some harsh chemicals that will strip your hair of any colour, but it also strips the original colour from your hair. Once you've used the kit, you'll find that your hair has an orange or light colour that isn't very attractive.
Rub a small amount of conditioner through your hair, rinse it out and let your hair completely dry before you move on.
Dye your hair back to brown using a permanent dye that's close to your natural hair colour. Follow the directions on the dye box as closely as possible, rinsing out when done. Then use a speciality shampoo and conditioner for colour-treated hair.
Ask a friend or relative to help you pick out a new shade of dye that's similar to your old hair colour. Sometimes your judgment might be a little skewed, while their opinion is right on track.
Keep in mind that pricey salon options will do almost the same thing described here. There's no way to go from black hair to brown without causing some damage to your hair.