I’ve been working on this draft for a week — it is quite long — and it’s usually accessible in the editor, but now it has disappeared! It is not published, it is not in any posted lists, etc. It’s gone!
Have you tried going to Manage >posts and then selecting “draft” in the status filter pulldown at the top and clicking the “filter” button? My drafts intermittently do not show up at the top of the editor. It seems they only show up there when the weather is right, or if I wear a certain color shirt.