I am a bit confused with so many replies. Forum is not allowing me to post fast !!! What I understand is I need to contact the merchant. I bought it from Cloud Mining Website. How do I contact them ?
Maybe if you can tell us which of the many cloud mining websites (of which the majority are ponzi scams) you visited and we could give you a hint.
I tried to send 0.02 BTC, whereas 20 BTC has gone from me. I can not afford this loss.
You are now at the mercy of the person that received it.
Need to get it back at any cost. In PayPal, CreditCard there is an option to revert a transaction. Why dont we have it in Bitcoin ?
Because thats how cash works. Bitcoin would not be bitcoin if it would just copy an existing certralized service. Please do not take this the wrong way, but: you should have read more about it before you aquired 20 BTC you can not afford to lose.