Please forget about extreme weight loss in such a short time.
It is not only unsustainable-you will likely gain more weight back after a while-
it is also very risky!!!
You can compromise your digestion, your G/I, nervous system, cognitive function, endocrine/hormonal system, etc.
Be wise and choose a life-long plan for health and fitness which will work.
If you are interested in the latter, please post again.
Don't let your short-term desires cloud your judgement.
There are NO fast fixes, period!
All the best.
I'm sorry to tell you but I don't think there's any way to lose 12kg in one month. You could lose probably close to half that if you eat around 1000-1200 calories a day (depending on your metabolism) and do cardio for 30-45 minutes 5 days a week. Lower body exercises also help a lot to burn calories. I hope you do this in a safe way and best luck at achieving your goals :)