saved games can still be seen but not accessed

Most people don't usually need to access other people's saved games. A better solution would be for Minecaft to ask if the other builders would like a copy saved to their accounts. Or the world gets saved on a server off of the system and can be accessed
via a username/password so that the world can still be worked on without being fractured by new saves.

when you are gold and save games to cloud storage,you can still access them if you turn silver.

Actually I believe if you don't have a gold membership you can't save games to the could and you won't see the saves in game, but you can still access it and move your saves to a portable storage device.

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So if you are only looking in-game for your saves that's probably why they are gone because you have lost access to your gold membership.

external storage would be a usb3.0 drive of your choice but still pricey, the cloud basically is that, your games saves are stored there so what ever machine you are on you can access the save seamlessly and all your games are accessible on any console for
download as long as your logged in.

XBL Silver accounts still have access to the cloud for game save purposes, so your games would still save on the cloud even if you let gold expire.