Which one is correct plural or singular for result in negative sentence?
He did not expect any result.
He did not expect any results.
Both are correct depending on the context.
If you expect there to be 0 or 1 results, then you can use the first one.
He tried to cast a spell, but he didn't expect any result.
If you expect there to be 0, 1, or more results, you can use the second:
He searched the internet for pictures of kittens, but he didn't expect any results.
This means he is expecting 0 pictures, 1 picture, or 2 or more pictures.
The second sentence sounds more natural though, as it is rare to use the singular form of a word with a plural pronoun.
However, you can use result in the second case, if you are talking about 0 or 1 results
He searched the internet for pictures of kittens, but he didn't expect any result.
This means he is expecting a result of 'there are pictures' or 'there are no pictures'.
Oftentimes, when people are talking about results, they are talking about situations, which can be organized in many ways. "We tried talking to her about her punctuality issues, but didn't get any results."
This is because the speaker didn't have one particular result in mind. There could have been a variety of responses that indicated the subject was making a change, and those results could be organized into many different sub-groups.