I am naturally blonde but have been dying my hair medium brown for nearly 2 years. I haven't dyed my hair again recently and I have decided I want to go back to my natural blonde colour. I have heard about lightening hair dyes but I'm not sure what colour this will turn my hair. Can you suggest anything else to lighten the colour of my hair or get my natural colour back?

In order to go from brown to blonde, you will have to lighten your hair with bleach and then apply a toner. Anything other than that will result in a red/orange color. You should consider letting a professional do the color for you.