father died of lung cancer due to result of smoking all his life at 52, child of his never looked into anything Legal wise due to learning disability.

My father was told by Dr's that he had lung cancer due to smoking, the operated on him and closed him back up quickly due to being to far gone, his lungs. He passed away in Jan of 1991 due to cancer of his lungs and other complications brought on by the cancer also. I never looked into anything at all Legally due to my own disability's and illness of low IQ and mental state. Is there anything that can be looked into as far as my fathers death due to smoking, Dr's, cancer, care? I'm aware that there is statues here, but I look at it as murder of a human being seeing what he went through and died as a result from it. And what about me? due to all my disability's and not understanding the Law and Legal parts of things of what to do and time limits of the nature. Any help that you may offer would be helpful to me, thank you for your time.