Both are wrong She doesn't have or (she has) = present. She didn't have = past I don't have or (I have) we don't have or (we have) They don't have or (they have) He doesn't have or (he has)
Both are correct, to mean different things. We just don't talk about it means We avoid that subject completely, but We don't just talk about it means Our involvement with it is not limited to mere...
"why don't you?" is a question. "why you don't" is a command. Why you don't? is not a correct question. Also it is not a command. Why can be used to give a suggestion or piece of advice eg. 'Why...