World Save does not work anymore.

Had been playing a singleplayer world on version Snapshot 19w07a. Suddenly today I can no lnger select my world in Singleplayer, yet the file is still located in my /.minecraft/saves. Don't know how to fix, hopuing my world isnt deleted or corrupted.Don't really know why this is happening in Minecraft... this game is how old, problems like this shouldn't be happening anymore.