Links to Relevant Wiki Articles(s):
You should first check your Trash folder.
Unfortunately if it is not there, we do not currently have a way to recover lost work or revert projects back to previous versions. .
One suggestion to try to avoid losing work in the future is to download your projects to your computer or make copies as you create them. This way you will always have a back-up of your work should something go wrong. We also recommend logging out as soon as you're done using Scratch. Leaving projects open on multiple devices can result in lost work.