I could not do nothing.

[Molly]

Are these sentences OK?

1. I could not do nothing.
2. I did not do nothing.
3. I did not not do anything.

[Haihao]

OK in spoken English, I think, such as I ain't know nothin!

[Barb_D]

They each require the right context.
1. You're a hero! You saved the drowning child at great risk to yourself. "Oh, I had to help! When I saw her out there, I knew that I could not [stand idly by] and do nothing to help."

2. You're a jerk. We all worked our butts off on this project and you did nothing to help us. "Hey! That's not true! I did not do nothing! I brought bagels to the team meetings."

3. Same thing, except instead of being told "and you did nothing to help us" it's "and you didn't do anything to help us."

I would say that #1 could work in writing, but #2 and #3 really will be far more likely in a spoken context.

[Yankee]

[Molly]

Thanks Barb and Haihao.