Weirdness Is Rampant, I Kill Ghosts in Sequence

My name is Gu Han, I am a doctor, no - I am a student. I was diagnosed as a mental patient six months ago. Since then, my memory has been "swallowed" in the past six months. Now I woke up unexpectedly and found that the world seemed to be "broken", that's right! That was no longer the world I knew. Weirdness is rampant, the world is upside down, this is a ghost land! I was put into a dispute, and I accidentally entered a strange letter bureau. There was an old man there, and he asked me to deliver the letter. Should I run, or do what he said - deliver the message?