Your "energy" is still there. It gets eaten up by worms and bacteria and such after you die. But your thoughts are not contained in simple energy alone. They are the result of the complex electrochemical reactions of the neural system of the brain. After the brain decays, there is no hope of ever being able to retrieve the information your thoughts once held. Since brain damaged people have diminished capacities for thinking, remembering, and other basic brain functions, it stands to reason that they would all stop completely if the brain's activity was damaged to the point of non-functionality.