I bleached my hair 12 months ago, today I dyed it light brown brown but it has gone green

Probably a chemical imbalance. Kind of like how when you have blond hair, it turns green after you get out of the pool (the chlorine effects it).

Because when going from blonde to brown, you need to add some base! Most brown hair dyes are bluey based. You should have applied a red dye to the hair (temp or semi) then dry it in. Then you should have applied the brown hair dye on top of that.

Please go see a reputable hair colourist to correct the colour. X

Had you used a brown with a golden base, that had 'golden' or 'sun' in the color name, it woudlnt have turned green. More than likely you used an ash shade, which have green bases. If the color is permanent, go to a Sally Beauty and buy 'Color Fix' [but use only parts 1 & 2-trust me on this =]. It will take the dark color out without bleach and won't damage your hair. And if you want to go light brown, again , look for a golden shade and stay away from ash shades. 3 long years of cosmetology can't be wrong ;]-Good Luck!

Anything I do to my hair it turns green

No my hair is dark brown with 15% graying on top I got perm in dec. my gray turned green. Now every time I wash my hair its green still today my gray is yellowish green.