Thanks gazumped.
Since my changes weren't on either my Windows PC or iPhone, I restarted my laptop hoping to find the changes where I'd made them, and they weren't there either! I was so glad that I'd copied and pasted them to Word and saved it, based on my reading of other users' complaints about this matter.
I'd love to have the time to open a support ticket, but I'd hope that Evernote employees might be monitoring this forum too.