How can i get nembutal or other barbiturates for insomnia?

A doctor's job ISN'T: to help people find dangerous drugs to take. Barbiturates stopped being prescribed because they are potentially lethal, highly addictive and have the worst withdrawal syndrome of any class of drugs on earth. Insomnia is caused by something - you find the cause and you treat it. You don't bury it with sedatives. See a sleep specialist/mental health specialist for evaluation, not hunt for bad drugs.