Minecraft snapshot worlds disappearing but are still in the Minecraft files.

One of my three snapshot wolds has disappeared of the interface of my game but is still in my files. This happened on the 29/12/19 at around 9 pm. I could access the world earlier in the day. I have not deleted the world at all. I also have a forge version of Minecraft on a seperate account. This bug just appeared out of nowhere and I am worried I have lost my future city map forever!