I just dyed my hair black-blue a couple days ago and I am really not happy with the outcome and I want to take my hair color back to a medium brown. I have a 6 and 1/2 G Lightest Golden Brown by loreal paris. What would happen if I used this on my blue-black hair?

If you apply a lighter shade of at-home hair color on dark hair, the color may not lift or it could result in a brassy red/orange hue. Going from black to brown will require some kind of hair lightening product. It's best to have your hair stripped or lightened and then deposit the desired color. Another option is to use a (cool) base ash hair color and a 20-volume peroxide developer to achieve results. The ash color will cut down the reddish tones and give you a brownish color.