Answer:
retrograde amnesia
Step-by-step explanation:
There is a classification that divides amnesia in two according to the memories that the person cannot recover or form. Thus, we say that a person has anterograde amnesia when he is unable to form new memories. On the other hand, we say that a person has retrograde amnesia when he cannot retrieve memories he could before.
An example of retrograde amnesia is a person who has had a motorcycle accident, hit his head and cannot remember facts prior to the accident.