Critical stage

My worst nightmare has come to pass. Dad, completely awake and able to hear/understand all around him, is able to respond to questions which can be answered using gestures, nods, blinks, etc. However, he is too weak to utter an intelligible sound or to hold a pencil, so he lays there with the most frustrated expression as he is completely unable to communicate his thoughts to those around him.

I need to devise a way to pry his thoughts from him using questions, but so far, am having no success.