Worlds disappear each time I reload the game

Loaded up Minecraft over the weekend, before I could play it needed an update. Once updated I loaded the game up and all my worlds have disappeared. I have tried uninstalling and reinstalling the game but nothing. The game remembers that I have over 300 hours on Minecraft but wont load my worlds up. I created a new world and started again, went to go back onto that new world today and that has disappeared too! I don't understand why its not showing my worlds. They are showing in the quick resume section on the launcher but not loading when I use it. Please can you shed some light onto why this is happening. Was running fine before this update.