I have somehow lost the panel showing my mail folder list (sent mail, drafts, trash, etc). This is very awkward. Can any one tell me how to get it to display? The hand book is of no use.
Check if the panel isn't simply collapsed. I mean if there is still and handler near the left side that you can drag to the right to have the folders again.
In any case you can try to reset the KMail configuration by deleting the file "~/.kde/share/config/kmailrc".