If you have purchased the phone in a country that bans FaceTime, there is nothing you can do - you can never get FaceTime on that phone,
Even if you are using it in a country that allows FaceTime, you still can't get it on that phone.
If you want FaceTime, then you'll have to buy a new phone from a country that allows FaceTime.
You only need to ask your question once and you don't need to keep repeating it.