It was my first experience.
I have been running a website using WordPress for several years, and there has never been an incident where the database was corrupted, even intentionally.
There were cases where the content would not display due to incompatibility with the plugin, so in such cases we were able to resolve the issue by going into the server and forcibly deleting the plugin.
This time, when I logged into WordPress, an unfamiliar alert popped up, something like "Your database needs to be updated" (I don't remember exactly what it was...), but I just clicked OK without thinking too much about it, thinking it was probably because WordPress had been automatically updated just before.
It said the update was complete, but I noticed it right away.
The article is missing.
http://nufufu.com/homepage/wordpress/wordpress-updates-database-needs-to-be-updated/
When I googled the update message, I found that it was the same as the one above. However, the version was different, and the plugin had not been installed, so it was clear that the cause was different.
When I looked into the server, I found that there were image files, including the images I created last month.
At this point, the only option was database corruption.
So I tried to restore it from "BackWPup", which I had been running previously.
I used this blog as a reference.
http://netaone.com/wp/backwpup-recovery/
What I did before the restoration
Unzip the backup file
What was different from the blog I used as reference was that it generated one daily backup on Dropbox.
Also, the compression format was tar.gz, but the contents are the same once you unzip it.
Check the sql file
After unzipping, there will be a file called .sql at the top level of the files. This contains all of your WordPress articles.
I opened it in a text editor and searched for keywords from articles I had recently written, and there they were.
Now we know that the problem was caused by the database update we just did, and that the article existed at the time of today's backup.
Now, once I've managed to restore it, I can rest easy knowing that the article will be resurrected.
Uploading the wp-content folder
I logged into the server and checked, and confirmed that even the most recent file existed, but I uploaded it just to be sure.
Importing a Database
Finally, I followed the instructions to import the sql file.
The Sakura Internet rental server I was using also had phpMyAdmin installed, so I selected the database where WordPress was installed and uploaded the SQL file using the import button.
The upload was successful and completed within a few seconds.
Display confirmation
It was restored safely. I'm glad I had a backup.
summary
Things like this happen sometimes.
English 
Japanese