Question: How can we change the following sentence into negative one without changing the meaning? 

> 
> He did everything.
> 
> 
> 

Can we change it into this: 

> 
> He left nothing undone.
> 
> 
> 

Or 

> 
> Didn't he do anything 
> 
> 
>

Answer: 
He did not stop until everything was done.
> 
> He left nothing undone.
> 
> 
> 

Does fit. Another choice might be:

> 
> There was nothing he didn't do.
> 
> 
> 

The second suggestion from the question does not fit.