My 5yo daughter has become very naughty and she has started back answering already. How should I discipline her?

oops, this is quite common actually, and trust me, all will be well if you take care now :) sometimes, at this age, kids start finding their independence and are more aware of their likes and dislikes. so, if you tell her to do something that she does not like, she will end up saying no straightaway. her intention will not be to back-answer you, but more to assert her will. one thing we need to take care of as parents is that we should stop using negative words with kids, and in general, a common word being 'no.' when you say 'no' to your child for so many things, she too will pick up the same and give it back to you. start by rephrasing your sentences and don't nag her. let her explore her independence, but tell her that if she has a problem with something, she needs to speak to you politely, and not rudely. very soon she will understand :)