The world has been deleted for no reason and cannot be retrieved

Yesterday, when I was playing with my friends, it was normal. Today suddenly there was a connection timeout. I wanted to say if there was a problem with the network, so I restarted my computer and started the game after it was finished. I found that the game was deleted for no reason and spent a lot of time on that map. On the completion of the achievement, it was deleted by the system in this way. I really feel that it is a waste of money.