My hair is naturally dark brown its was bleach blonde for 8 yrs. Now I want to dye it back blonde?? Is it possible?? Will a blonde home dye kit dye over the brown, which is bleached under the brown??

You cannot "dye" your dark hair blonde. Blonde hair dye does not cover over dark hair. You first need to lift the dark pigment, then tone to the desired shade of blonde. Please consider seeing a professional :)