I opened Minecraft and I went to log into my world, I had 3 worlds the day before. I looked to go into my world named 'Elaine' I had made great progress in it, but I clicked play and then it was not there. I tried re-opening Minecraft, and still no. I was very annoyed. I was a mobile player until now and had NO issues with it. This is my first time playing on PC, so I have a testing world to help me learn to play called 'Testing...1...2...3' and my first world to try survival called 'Survival with Vault Tech' and obviously my world 'Elaine'. I don't know if that information will help, or if it is just an issue with my Minecraft. 

Thank you and have a nice day.