I was horrified to open my Voice Memos app earlier this evening and discover a distinct absence of recordings, as well. I downloaded iExplorer and, without purchasing or registering the software, was able to recover my memos from a backup.
Download here: http://www.macroplant.com/iexplorer/
Upon opening iExplorer, chose "Continue with Demo" in the bottom right corner. Chose "Backups" on the right, under "Explore." A dialog box will prompt you to "Use Last Backup" or "Refresh." Click "Use Last Backup."
From the list of folders you now see, open "MediaDomain>Media>Recordings." Your voice memos are the files of type M4A. Simply select those files and drag them into a new folder on your desktop. You can then add the files from the folder on your desktop to iTunes and make a playlist or whatever else your heart desires. The dates and times of the memos seem to be lost, but at least the recordings themselves were salvagable. Hopefully this process resolves your issue. Good luck!
Also, I think it would be in our best interest to take a lesson from this, and manually backup our recordings on a regular basis from this point forward.