Im certainly no expert.... if a 'playlist' has gone..end of... then the regis. should still be there to support them in your registrations .
So you should be able to create a new playlist again.
Or alternatively, if the playlists are there and your just running into an empty playlist, when you open them, then likely it is the regis that are not there and cant be found to run the playlist when you try to open it as playlist needs them to operate.
As far as I am aware ... Playlist is simply a 'list' and is just reliant on registrations and their contents for it to work.
As Eileen. says, if its an MF file, which was converted to playlist, just re do it again. This is quite easy and quick to do ...but it would be interesting to see if the registrations also created by an MF conversion to playlist are still there on your board from previously....??
keith