Harry had been thinking. He had been thinking for a while now about how his life has come to this point. His friends and family are long since dead while he doesn't age. The year is 2400 and it has been 302 years since he become Master of Death. He has seen many generation of potters after his kids. He had two kids with his wife Ginny, and even though he loved them with all his heart, he never felt complete.
Ginny died on July 31st 2020 due to a new Dark Lord. Then Harry had discovered that he had been potioned with love potions for several decades. With her death he tried to raise his kids the best he could but always felt that his life felt empty. Then he had realized he had loved Hermione, but with her going back to the muggle world after a messy divorce with Ron he didn't want to drag her back to the wizarding world. She was also potioned up to her eyebrows. She managed to escape and fled directly into the muggle world and no one found her after that.
Harry for the last 20 years has been being experimented on by the muggle governments and he had a feeling that he was the last wizard alive. The muggle government eventually found the wizarding world because of the many Dark Lords killing muggles. When the governments found out they deemed it to dangerous to be kept around so they destroyed wizarding society. They only couldn't kill one person and that was Harry Potter. And that was why he was chained in a basement somewhere malnourished and without a magical core but still immortal.
The muggle government found a way to extract magical cores humanly without killing the person which they did for any muggleborn children.
There was a long silence where nothing happened when Death appeared before Harry. Death and Harry spent some time conversing with Death telling Harry that Mother magic was not happy. They then made a deal that Harry would go back in time to when he was eleven to change everything.