Disappeared for five years, my ex-girlfriend's house is in my posthumous photo

Lin Yi, an anonymous national scholar, has led many breakthroughs in scientific research.
He was secretly recruited to the Northwest to develop a new type of engine, so he disappeared for five years!
Five years later, Lin Yi completed his mission and returned to the city, but accidentally bumped into a little girl on the street.
The soft and cute little girl blinked her big eyes and looked at him: "Uncle, you look like my father."
Lin Yi, who has been dealing with blueprints and cold machines all year round, showed a rare warm smile: "Then why didn't your father come to pick you up after school?"
Little girl: "My dad died..."
Lin Yi was soft-hearted and worried that the little girl would be in danger, so he sent her home.
Unexpectedly, as soon as he entered the door, he saw a black and white posthumous photo hanging on the wall, and the person in the posthumous photo actually looked exactly like himself?
"I heard... I'm dead?"