Since all files are stored locally on the device, we can't restore a deleted file.
If you are using an iPhone, iPad or iPod:
When you delete a project, it goes into your Recently Deleted folder. If you change your mind or accidentally delete a project, you have 30 days to get it back. Open the Files app and go to Locations > Recently Deleted. Select the file that you want to keep and tap Recover. After 30 days, your files are removed from Recently Deleted.
If you are using an Android device:
At the moment, Android does not have an option to restore a delete file.