I don't think the sort is undo-able.


A backup of your Outlook .pst or .ost data file MAY contain folder sort criteria. It's worth trying.



If you don't have a backup, or if replacing your current Outlook data file with a backup doesn't help, there are two ways forward:


1. Manually reorder all of your folders.


2. Write macros to automate the task of reordering your folders.


The second method is viable because there are sequences of keys to move folders up and down the list. Of course, you can manually press the key sequences, and once you've memorized them, this approach is probably faster than drag-and-drop. But the point of using macros is to allow you to do this by pressing two keys: one key to move a folder up the list, and another key to move a folder down the list.


My guess is that macros to move folders can be produced in a few minutes. I estimate that using macros would enable you to restore order to the list 10 or 20 times faster than by dragging-and-dropping.