My Younger Sister Was a Genius is a Manga/Manhwa/Manhua in english language, Drama series, english chapters have been translated and you can read them here. You are reading chapters on www.mgeko.cc fastest updating comic site. The Summary is

Yoon Hajoon, who struggled to pursue his musical career despite his iffy talents and ended up sacrificing his own family along the way, " If only I could turn back time...! " One day, after living with regrets and alcohol for a while, he woke up and found himself had returned to the past. Just then, it dawned on him. The fact that my younger sister is a musical genius...! Now is the time to turn my life around, that is by producing my younger sister into becoming the best singer!