TG
Try navigating to this folder. (You will need to set windows to see hidden folders)
C:\Documents and Settings\John\Local Settings\Application Data\Identities\{61FB18BE-8591-4B92-BFBB-BAC192EA1ACC}\Microsoft\Outlook Express
If the Sent Items file is empty or missing then all is lost.
If you have made a back up recently ? then you could copy the back up file into the folder above to replace the duff file.
If you know all of the above – Please ignore and I’ll return to my hutch