Seed no longer exists, world corrupted

We’re having this issue since v1.16 (or maybe 1.15) and cannot find a solution yet. When we try to load our world the game stay stuck at the loading resource pack process. In the end we get a message saying unable to load this world, other times the game crashes.. We tried everything, our last hope was to upload the world on a realm and then try to do something from a Pc. We were trying to create a new world with the same seed to overwrite the corrupted files with the new ones, (as this dude does on YouTube https://youtu.be/dARRKHrt1xM)but our seed does not exists anymore..! The game creates a totally different world, even if the seed is the same as our world. So we are stuck here. Any possible solution..?