Midi data in Logic Pro X region has vanished?

Hello. Hoping for some help. I have a project built around a primary midi track in Logic Pro X..."Bossendorfer Grand" and its piano/score editor counterparts...all have gone missing...the regions are still there, but no data.

Not ruling out accidental deletion as there was someone helping with the project last time it was open, but very careful to NOT save and changes made when a project is being played with for learning/experimental purposes.

If anyone knows why it has gone missing (this particular track/region was not being played with during the last session) and what I can do to get it back, I'd be most grateful...the project is dead without it.

Is it somewhere in a wastebasket or external HD backup? How could I find it and reinstate?

Thank-You.