Your pre-compacted email folder files (with .dbx extensions) should be in your Recycle Bin; you can restore them from there. Make sure OE is closed when you do the restore. Note that this will overwrite the folder files there now; if you've received or written any new messages since the problem arose, make sure you move those messages to a folder that you won't be overwriting with the Restore function.
If you don't find them there and will not be able to recover, it's possible your dbx file is corrupt that's why u can't see the emails on that folder. There is free download OE-Mail Re