What's the negation of "One of the sentence is false"? I think is "Any of the sentence is wrong" but I'm not sure, maybe "Any of the sentences is right"?
If we interpret the word "one" as meaning "exactly one" then negating "one of the sentences is false" means that we should not have exactly one of the sentences false thus we should have the sentence

$$\text{All sentences are true or more than one sentence is false}$$

We could of course interpret "one" as meaning "at least one" (something which may be argued to be the most common mathematical interpretation) in which case we would translate the sentence to
$$\text{All sentences are true }$$
Which is what you answered (formulated a bit differently).
To negate a sentence, we negate the primary operator. For example, to negate "$\exists x. f(x)=4$", we negate both the quantifier and the "=" operator but leave $f$ alone:


  Original: $\exists x. f(x)=4$
  Negated: $\forall x. f(x)\ne4$


The quantifier in your example is "one of", that is, a 'there exists' quantifier. The primary operator in the sentence is "is". To negate the sentence, negate the quantifier to get 'for all' and the operator to get "is not" (or "are not"):


  Original: One of the sentences is false.
  Negated: All of the sentences are not false.