Try this - I can't guarantee it will work
Search for .dbx files, create a folder on your Desktop called Mail and drag (Move not Copy) all your .dbx files in the Search window to the Mail folder on your Desktop.
Close your search window. Attempt to open Outlook Express.
If you are successfull Outlook Express will recreate your system folders which include:
and the Folders.dbx file
You should then be able to Import your messages from the desktop back into Outlook Express.
File>Import>Messages>Microsoft Outlook 6>Import Mail from an OE6 directory>Browse to your Mail folder on the desktop,
leave the setting as is for all the messages or select the folders you want to Import.