Assuming you're using Outlook (what version, by the way)... one of two
things occurs to me:
1. A filter has been applied, making them "invisible" in the current view.
To see if this is the case, right-click a blank area in the Inbox listing
and choose Customize Current View from the popup menu. Next to Filter, you
will see the word "Off" or something else. Which is it? If it's not Off, you
might need to investigate to see whether you turned it off, or if you
might've accidentally selected a different view. You can click Filter and
choose Clear All, but if you've simply applied the wrong view, then you
might not want to do that. You might want to reapply the original view,
instead. To do this, press Escape to clear the dialogs, then look at the
Current View tool in the Advanced toolbar.
2. AutoArchiving has kicked in, and those messages are now in an archive
file. From Outlook's menu, choose Tools - Options - Other tab, and click the
AutoArchive button. Is Run AutoArchive turned on? If so, then look under
Move Old Items to see where the archive .pst file is stored. You can open it
and drag the messages back into the Inbox. If you don't like AutoArchive,
you might want to turn it off.
Hope this helps...
