Found!

You are locked in. Outwardly, you are as good as dead -no movement, no reactions, no emotions, just bodily functions driven by machinery.
    But you are conscious, only there is no way you can tell the world. You listen to conversations around you -it's an election year, it appears-, you agree, you disagree, you strongly disagree.
   You know your family is grieving. You'd like to let them know you are there, but you are locked in, as if in a different plane of existence, in a parallel universe.
   One day one of the voices you spend your life listening to to pass the... time?... addresses you.
   "Can you  hear me?" it says, incongruously. The owner of the voice knows that, whatever the answer is, you will not answer. However, it is clear that the owner of the voice thinks that the answer is yes.
   The voice says something odd.
    "Imagine you are playing tennis."
    You do. You have never played, but you have no trouble imagining the sequence of movements needed to hit the ball. While you're at it, and just for the heck of it, you imagine the sun on your face.
    "Now imagine you are walking around your house. Show us around."
    You go upstairs to your room. "This is my room," you'd say. Then down to the yard.
    Elation in the other universe.
    They make you repeat the tasks. It has been so long since anyone asked you to do things. Your family talks to you, but they never ask you to perform tasks. They do not really believe you can hear them. Now someone is requiring you to actually do things. How do they know you are responding? You tell yourself they probably have you hooked to some kind of brain scanning machine.
    You wait for more instructions, but the voice just wants you to perform these two tasks over and over. Are you dreaming? What does dreaming mean in your universe?
    Then you understand.
    "I'm going to ask you some questions", the voice says. "I want you to imagine you're playing tennis if the answer is yes and imagine you're walking around your house if the answer is no, ok?"
    Clever, you think (how does that thought show on the brain scanner?)
    "Is your father's name Thomas?"
    You go around your house.
    No.
    "Is it Bob?"
    Tennis. Yes!
    "Do you have brothers?"
    Whack! You hit the tennis ball with all your might and mark a point. Yes! Yes!
    "Do you have sisters?"
    A quiet walk from the yard to the living room. You don't have sisters.
   "That is correct," says the voice, barely containing its elation after several more questions. You are elated too.
    They have found you.
    Time passes, you don't know how much. Time means little to you in your locked-in universe. The voice comes back. You can sense the hesitation when it says:
    "This is something your family wants to know. I don't know how else to put it. Should we discontinue life support?"