Can't access my worlds.

I opted out of the Minecraft Beta 1.13.1, and uninstalled and reinstalled Minecraft, but when I when to my worlds, they were gone. I checked in the storage on settings and found them, but when I selected them, I only get the option to delete them. (The worlds were created before I entered the Beta, and I didn't use Beta content in any of preexisting world) What does this mean? Are my worlds gone? Are they locked in till the next update? Can I get them back? I need help with this.