The world is not fully synced or is corrupted

My favorite world has been showing that it's corrupted and or not fully synced. I got a different Xbox bcuz my other one broke, synced my other worlds but the one I wanted to play the most didnt sync and I can't ever open it. I've tried everything in him the book to fox. Only Mika good can find a way, I speak for thousands or people who've lost insane worlds with years of time.