Are MIDI notes lost?
I’ve accidentally deleted a track that contained MIDI notes. Do we know any way of getting it back? (I’ve spotted it has no File Name in the track itself, as a .wav file would, and I’ve looked in the recycle bin, but no joy)
Are there ‘any’ midi files in the song folder?
No .MID files in the song folder. Your question suggests there should be, but i can’t see any .mid files at all in any of my song folders. Is that surprising?
Recycle bin?
It’s a good habit to export a midi file on occasion.
For the future if this happens all you have to do is EDIT>UNDO and it will come back. 
dontcare.