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

I am sorry but I have to confess this that I felt really glad to see your query. I am also a mother of a five-year-old girl and I have experienced that till last year she was a coy, no-fuss baby, and she has suddenly turned naughty. Not only this, she at 5 answers back. And in my case, I feel that she answers back because when she was younger I used to tease her and when she would scream at me, I used to love those little expressions she made and things she used to say being angry. That time I found that cute but now when she is growing up I find the same behaviour unacceptable. But I am sure, you must not have been this mean to her, so I suggest ignore her when she answers back if things turn bad, but otherwise let her calm down and sweetly tell her how bad you feel and how she hurt your heart by being rude to you. This is what I have started doing. I let things cool down and later I tell her that mumma feels very sad in her heart when you talk badly. I do role play, and scream the way she had done, and then she feels embarrassed and promises me never to repeat it. Ofcourse, she repeats it, but this is a practice which I think if we continue her behaviour will soon change. Try it with your daughter. https://www.positivediscipline.com/articles/45-year-old-who-talks-back