Can i loose 10 to 12 kg in a month with a only walk for 20 minutes and diet with not more than 40 g carbs a day can i loose it?

Too rapid: Unless you were quite morbidly obese & had to lose weight rapidly for a particular health reason - I would recommend a moderate goal. Slower is better. By the way - walking for 20 minutes a day does not burn many calories. Weight loss is not just about amount of carbohydrates - it is more about the fact that calories burned need to exceed calories consumed. Take care.