I was editing while trying to convert to https from the management screen with WordPress
Then, on the way, I couldn't open the site at all.

Probably in the management screen ⇒ settings ⇒ general settings

>WordPress address (URL): http ⇒ https
>Site address (URL): http ⇒ https
The I think that's because you've been, but I do not know how good and correct how can not be logged.

When I was investigating, I tried the following,
The login screen is already CSS (maybe) not working, so
The login screen came out with no layout.

When I checked the homepage, I found that the site with only text was displayed, probably without the layout and colors set by CSS.

Excuse me, but could you please teach me?
Best regard.

I edited wp-config.php.

update_option ('siteurl','http://example.com');
update_option ('home','http://example.com');

* Example.com is the URL of your site.

I edited the theme's functions.php.

update_option ('siteurl','http://example.com');
update_option ('home','http://example.com');

The above 2 files have been uploaded using FTP software.

After the above

The notation of wp-config.php may have been wrong, so I edited the following.
define ('WP_SITEURL','http://example.com');
define ('WP_HOME','http://example.com');

The login screen appears, but the login screen collapses and
If i try to log in in that state, the message "Redirects have been repeated." Will appear.
I tried changing the browser and clearing the cache, but it didn't work.