Had a keratin treatment done yesterday. Coloured my hair 1 week before and it's turned copper. Help!

Hi is you 3 days after was over ?
Sometimes before you wash and condition your hair for the 1st time to colour can look different or lighter.
Wait the 3 days as advised and see what colour it looks if it still looks copper use a tempory colour.
If it affects the treatment so be it, its more important you look good on your big day :)

For many perhaps it really is of great benefit, for some not. This is not a treatment you should skimp on with regard to following the trend. There are harmful products on the market; nevertheless, I always prefer safety first by using totally formaldehyde-free formulas.
Ahhh! My sympathies are with you about your awful experience! There is nothing you can do to repair your damaged hair. You can only prevent damage. Consider using a lot of TLC for your hair. Go for moisture moisture moisture!
Shampoo with a gentle shampoo, which has some salt so your curls back. I'd go for Giovanni Tea shampoo ( walmart and/or target).
Do a hot oil treatment of olive oil and honey before you shampoo.
DC 1-2xs a week for the next 4 weeks.
Give it a month! I promise it will be better!

It really depends on the colour of your hair, but if you are light brown to black, you can put a temporary colour over it, like Wella's Colour Fresh. This has no peroxide or ammonia so won't disturb your Keratin treatment, it just lays over the outer layer of your hair. It washes out in 2-4 washes.
Best wishes for your wedding day!