Ok so I've had bleeched blonde hair for 3 years and today I bought a non-permanent brown hair dye, I'm an expert at dying hair, but never from one colour to another, and I dyed my hair brown and its gone brown but with a very noticeable green tint, I have school in 2 days, and I need to fix my hair, I was thinking to dye it back to blonde tomorrow but I think it might damage my hair, any tips to get rid of the green until it washes out?

Sounds like you chose a hair color that has a green base. Some "neutral" and "ash" colors will have a green base to counteract the natural warm undertones in human hair. Since you have been bleaching your hair for so long, you have stripped it of all the natural pigments, including the warm undertones. This means that all of the green base in the "dye" will show up in your hair. Since your hair is most likely very porous now from years of bleaching, it acts like a sponge to soak up the color. It will also let go of the color just as easily. Wash your hair a couple times with dishwashing soap or a clarifying shampoo. Some of the color will fade. Then you can color over your hair again with a color that has "golden", "red", or "warm" tones. You MUST have at least one of these tones present to color bleached hair with a good result. Of course, I ALWAYS suggest professional help when making a change in coloring your hair. Especially if you have an issue like this one. Once you get your hair to the desired result, I would also recommend having a colorist "seal" the color with a color sealant, and for you to invest in a deep conditioning treatment and a trim to keep your hair healthy after all it has been through.