Return (2007)

A young boy experiences anesthesia awareness while undergoing surgery. Unable to respond because of a muscle relaxant administered to him, the boy is severely traumatized. The result is his killing of a young girl soon after the operation. The boy is admitted to a mental institution, and with the help of a team of psychiatrists, his memories are blocked and he is able to lead a normal life. Twenty years later a series of events unlocks his memories and once again transforms him into a murderer. As the killings continue, the secrets from twenty years earlier are slowly revealed.

Source: TMDb