I'm sorry this happened to you. There are so many scary stories with these keratin treatments it's insane

For future reference, there is nothing you can do to repair damaged hair. You can only prevent damage. Once it has occurred, there's nothing you can do. It's all an advertising gimmick--hair products that say "repairs" are really just taking advantage of good marketing. Hair is dead. Just like if your nail cracks, you can try everything to prevent it from breaking, but it will break anyway, you can never mend the chip/break

Try a lot of TLC for your hair, but the truth is that will not help it come back. You will probably have to start over

I'm sorry and I hope you feel better about it soon