On two separate occasions the world I ahd been working on has disappeared and I cannot get them back. I have tried to synce old worlds but that did not work. This is very frustrating as I had put a large chunk of time into both of these, only for this work to be taken away
Related issues
Comments

Thank you for your report!
We're actually already tracking this issue at MCPE-35364, so I will resolve and link this ticket as a duplicate.
If you would like to add a vote and any extra information to the main ticket it would be appreciated.
If you haven't already, you might like to make use of the search feature to see if the issue has already been mentioned.
Quick Links:
📓 Issue Guidelines – 💬 Community Support – 📧 Customer Support – ✍️ Feedback and Suggestions – 📖 Game Wiki