So I've been dying my hair a dark brown color forever and I wanted to go for a light brown/dark blond color. I bought this dye that's supposed to do just that from a beauty supply store, where professionals shop, it said it would lighten hair up to three shades. Well it worked for about the first three inches of my hair and then the rest is still a relatively dark brown. Now just short of getting it done professionally, is there something I can do about it. I did it two to three weeks ago.

If you want to from brown to dark blonde, you will need to pre-lighten your hair and then apply the selected color. Anything other than that will result in brassy or unpleasant color. It's best to go get it done professionally.