Amnesia: 1: loss of memory due usually to brain injury, shock, fatigue, repression, or illness 2: a gap in one’s memory 3: the selective overlooking or ignoring of events or acts that are not favorable or useful to one’s purpose or position (Webster).
Amnesia, as Webster’s definition #1 says, has been the subject of many stories — real or imagined. An outstanding example is the true story of Anastasia, the Russian czar’s heiress who had amnesia and had forgotten who she really was.