Forgotten (2017)

Other name: 기억의 밤, Gieokui Bam , Night of Memories , Night of Memory , Recall the Night

Synopsis: :
After moving into a new house, the eldest son of the family, Yoo Seok, is abducted right in front of his younger brother, Jin Seok. After 19 days, Yoo Seok suddenly comes back, however, he starts acting like a different person. Suspicious of his brother, Jin Seok sets out to reveal the hidden truth behind the abduction and what happened to Yoo Seok during the 19 days.
(Source: MyDramaList)