You'd need unlimited money and hyperadvanced future technology. There's just no way to get things lined up and no way to reconnect any of it and no way to reclaim or reattach any of the tiny bits of silicon that preferred to become dust rather than take sides.

If you had enough money to convince AMD to sell you the tapeout, and if you could hire a fab using a similar process, you could make a new CPU. Other than that... probably not.

The next best thing would be buying a replacement.

Maybe, you would have to buy AMD or make them sell you the schema/chip masks for this chip, then buy ASML and ask them to spend the next 10 years figuring out how to regrow silicon on the broken chip layer by layer while also re-exposing the missing part. You would probably also need to buy a chunk of TSMC since this would require advanced chemical processing such that you can re-grow and re-expose a part of the chip without destroying the existing part. You would also need a lot of investment in scanning technology, to measure exactly what the current state of the chip is and what needs rebuilding and where.

You could change the chip on the substrate, but why, you could just get another cpu...

nope

Just jam the piece back in there, I'm sure it'll be fine. /s