Hi Mala,
Any flat tummy workout dosent only include tummy resistance exercises but it should also include some cardio training exercises to normalize your body fat percentage. Once your body fat percentage is in normal level we can work on toning your tummy muscles by doing weight training exercises. Weight training exercises are like crunches, reverse crunches, heel touch, oblique crunches, abbs cycling etc. We need to do these exercises for 30 min in a day for better results.