How to fix green hair after bleaching?

Your first mistake was not using a colour remover to get the old black dye out. That would be the logical next step now, to get the old dyes out and see what your base is. You may need to do more than one, but colour removers aren't damaging, just drying.
A pic of your current colour would really help.
Are you still aiming for a dark purple with light purple highlights? Or do you want blonde?

I was told to go bright colours you need to be some sort of blonde? My natural base is a dirty blonde I've never liked it much, so always dyed it dark until I bleached it for the red. I can't get a pic right now. But imagine a purply pink at the roots then it goes matchy green and light orangey brown. (My hair is shoulder length.) I really want the deep purple but have no idea how to get my hair one stable colour let alone purple haha!

Here you go 🙂

You definitely need to use a colour remover, to try and get the ends lighter.
You don't need a pale blonde base for a dark purple, a good direct dye like Special effect Deep Purple will take well over a gold base. You need to work on getting it even first.

woukd a colour remover take it all out? I've seen the colour b4, would that be any good? (Thankyou for helping me out)

It will definitely help, you may need several rounds to get as much out as possible. If the hair is stained from the black dye then nothing will get that out, not even bleach. Staining is more likely with dark dyes over a bleached base, but with colour remover you should be able to get to a copper colour at least.