Fantasy: the Plot Is a Bit Confusing

Lin Feng was originally an online author. One day, on a whim, he took out a book he wrote in junior high school. After reading it, he felt it didn't make sense, so he spent the whole night revising the manuscript, and then: He traveled through time and became the protagonist of the little book he wrote in junior high school. I thought that with my omniscience and omnipotence, I could have a smooth life, but I didn't expect that the plot would not go according to what I wrote... The old man who originally gave him equipment before his death actually turned his sword on him; The magical secret book that was supposed to be obtained has turned into a shabby book on the street; The heroine who originally liked him turned out to be......