No question arises as to why it happened, because it never happened finally. What is required in a person is psychoanalytical treatment, as they call it. Something is wrong in the thinking itself. Something has happened to you, and you will know it when it is rectified. So, if nothing is happening, then really my mind is not here.
Nothing is anywhere.
If you really believe that you don't exist also, you will have no problems, but you cannot believe that you are not existing. That is why these questions arise. You try to abolish the consciousness of your existence also, and let us see what happens. You will melt into the Absolute at that moment. Then you will never raise questions afterwards.