|This happened to me.|
If you revert a published web page or blog post to draft mode for whatever reason and then re-publish, Blogspot will change your URL and not tell you! At which point anyone arriving from a search engine or any other source will immediately get a 404-file-not-found. In other words, you've lost everything. That post (whether being used as a web page or a blog post) no longer exists to the search engines, social media, or anywhere else your former URL is listed. All gone, you are back to zero. Your former URL is gone and your new URL will have to be discovered and shared all over again.
To clarify, this is about what Blogger calls "posts"; I don't know if Blogger does the same thing to what Blogger calls "pages", nor do I intend to find out. Also, I'm not talking about the usual editing/updating routine we all do to our published posts (whether being used as a web page or a blog post). I'm talking about the reverting of a published post to draft mode and then republishing it. Don't ever do that. If you do, you have effectively just murdered your web page or blog post. If you have done it recently and been wondering why your traffic for that post suddenly cratered to zero, that is the reason.
Fortunately I found a way to at least partially salvage the situation. You can go to "Settings" and then "Search preferences". There you will find "Custom Redirects". You can put the former and new URLs there. So at least I got my traffic back, but I'm sure the search engines are thrilled, now that they will be thinking I've got duplicate pages on my website. And I'm wondering if my search ranking for that page is going to drop dead when the redirection is discovered.
Blogger needs to implement a warning prompt when a user is about to do something that will change an URL. I mean seriously, they are not idiots and know how serious an URL change can be.
Why couldn't this have happened to one of my low-traffic articles? No, it had to happen to one of my top performers. The life of an online writer..., where the adventures never end. Oh, well. At least I hope this post saves a few kindred souls from similar fates.