Read chapter 64. He did not lose his memories when he crashed, he remembered her and he asked his family about jiyoung but they told her that she died. Later he hired someone to investigate and the outcome was the same. He got super sad and he drove his car off the road.
Omg omg omgggg that means he tried to kill himself and lost his memories, i thought he lost his memories in that accident with jiyoung. Omgggg..!!!!!!