It was a novel about a female protagonist who died in a car accident and traveled to ancient times. She was reborn in a coffin and became a ghost.

The book,"Imperial Empress Leng, Please Take This", fits your requirements. After the female pig died in a car accident, she traveled to ancient times and became an abandoned empress in the Cold Palace. Then, she began to lead the medical revolution and successfully trained a unique loyal dog. It looks like a very interesting novel. You can try to read it. I hope you like this fairy's recommendation. Muah ~😗