To undo an edit -
Select the Undo icon (curved arrow pointing left) beside the canvas.
Click Undo multiple times to revert multiple steps.
If the button is unavailable, there are no edits to undo.
To recover an earlier version of your document -
Select File > See Version History. Versions are auto-saved every few minutes.
Click Preview on your saved versions to find the one you want.
Select Restore This Version in the toolbar.