Missing notes on MacBook Air
You might be able to see or recover some of your lost Notes.

Open Terminal and paste this:

cd ~/Library/Containers/com.apple.Notes/Data/Library/Notes
strings NotesV1.storedata | grep body | open -f


That should show you all your notes in text file, from where you can copy the missing one.

Terminal is a application located in the Utilities Folder under Applications.