There was a problem that the Web stopped from this Monday and it was not displayed.
I searched and searched for keywords such as "WP management screen does not appear suddenly", "Cannot log in to WP", "Page not found", but the method introduced on the Web (cookie deletion, wp_config) I couldn't recover no matter what I did (additional changes, cache plugin-in purge and stop).
After 6 days, I was in trouble, but I finally recovered by rebuilding the WP.
Rename the existing WP installation folder and reinstall WP.
In addition, I deleted MySQL and reinstalled it anew instead of overwriting it.
I only updated the latest version of WP, installed the UpdraftPlus plugin, and restored it with the backup data that was on Dropbox as of the end of last month.
I overwrote all the files that I had done with InpsydeBackWPup before UpdraftPlus to the existing folder by FTP, but it did not recover.
Since it was not restored by overwrite restoration for each file, I predicted that database restoration was indispensable, took the plunge and deleted the old database, and restored with Updraft Plus.
At this time, the old WP folder (WP_admin etc.) that should have been renamed without deleting it has disappeared.
Even if you have backup data of UpdraftPlus, you can't do anything without the management screen. FTP alone has its limits.
At the very least, I thought it would be possible to work remotely because it is both a local and UpdraftPlus app, but I couldn't operate it without the WP itself, so I decided that I had to reinstall it.
Not all the information on the various web sites is correct.It depends on the environment.The database was completely broken by the postscript update command of WP_config that was on some site, and the CSS was also broken.