Are the emails missing from just the Inbox? Do you happen to have a filter in Outlook set which may be not showing your entire Inbox contents?
Have you checked the Deleted Items folder? How about the Recover Deleted Items view (go to Deleted Items, then Tools > Recover Deleted Items)?
See more: https://groups.google.com/forum/?hl=en#!topic/microsoft-outlook-pst-file-repair-tool/8KDhnha9VJs