I seem to have lost a whole "chunk" of tasks & sub-tasks I had entered under a project. Yikes!! Is there any way to retrieve "lost" info or go back/undo?
We have the Backups area under Todoist Settings (top right gear icon) and it could be there, but there shouldn't be need for this. Were you ever offline while adding of these tasks?
Are you sure you didn't sign into a different account while doing so?