My Flagged mail box does not show mail

I recently changed email providers. I backed up some notes into MY MAC but neglected to move some flagged messages to the Hard Drive. The Flagged mailbox shows that there are a number of Flagged messages. However, when highlighted it does not show the messages. Assuming that during the transition to the new mail provider those notes have been lost, how do I get the number of messages to accurately show the number of notes that are actually in the mailbox? I cannot find any folders within the various mail libraries. It would be cool to actually find those flagged messages, but that may not be possible.