I'm 40 Kg, 170cm, I'm Thin And My Body Loks Like A Corpse. I Tried All Kinds Of Weight Gain, And Also Visited Doctors. They Said I'm In Health, But I'm Angry About This Deadly Corpse Body. Is There A Way To Gain Weight Fast?

I was in your place about 6months ago.
It was impossible for me to gain weight with such deteriorated health condition
I mean, the body does not metabolize the food normally and if you try to gain weight with excess amount of food, it'll only be dangerous - there are such conditions called the re-feeding syndrome
it is impossible for a women with 170cm in height to be healthy at such low weight.
I bet you're not even menstruating..
I got help from being in the hospital for a while
until I was admitted, I never realized my heart rate at night would go down to the 30s. And that could cause heart failure in my sleep, or in unlucky cases, sudden death while doing normal activity during the day.
I would suggest that you go and see an eating disorder specialist. They know best about underweight bodies and you'd be surprised to find out what kind of things that you're making your body go through.
I've seen many people who are not actually anorexic, but benefit from seeking help by eating disorder doctors.

It's probably not the best idea to try and gain weight fast. You could try working out hardcore to build muscle. Eating three times a day with snacks in between. You could also have a fast digestive system which in most cases restricts weight gain. But if you are desperate(which I don't encourage) eat junk food, snack in the middle of the night, and drink dr. Pepper.  Trust me, I know this because I'm trying to lose weight.