Anything with not in English is negative. So they can and are all used negatively. CANNOT NOT do anything is considered to be a 'double negative' in English and is not used nor encouraged to be used, in the classroom. Double negative colloquially speaking does take place but it is controversial and causes many disagreements. It is the same for could not not do X in English it would be considered a double negative. It is a subject that can become very complex and involved. You can ask negative interrogative questions in English, that is like this "can you not make so much noise" "can you not at least try" Note there is never two nots or two negative words in one clause. Using Turkish as an example English does not have exactly the same 'can you not not type' questions, there is only a small overlap sometimes. They do not translate into good English in the grammar books.

After your explanation of what you are asking; it is "are you unable to do x?" "are you incapable of X?" "do you not have the ability to do X?" no double nots. "are you UNable to do x/?" UN=the not in the sentence above. both sentences mean the same.