Names of voice memos wiped after iOS8 upgrade - can I get them back?
You could try using the free software iBrowse to open your iPhone, then open the Recordings folder, and look for Recordings.db. This can be opened with SQLite Database Browser. Open the DB in SQLite Database Browser, then Browse Data and find your filenames and their titles.

If they are not there, you could try making a new Voice Memo, and repeat this procedure. Now see if you can manually edit the DB to make the rest of your files match the format used to name the new Voice Memo. Ultimately save your .DB and copy it back to your iPhone using iBrowse. Make sure to save backups in case your iPhone doesn't like your hand-edited database.