Worlds on Minecraft bedrock Xbox One keep on being deleted randomly and I no longer have access to them. Is there anyway to get them back?

After playing a world for a few days, I go back to play again but then the world isnt there anymore it gets deleted by the game system and i can no longer play on the world. It has cost me lots of hours which i had put on the world which has been deleted. It only affects worlds that I have been playing on the new aquatic update or the world that i play continously.