Changed site URL… All I see is "No Input File"

Hello al

I am fairly new to WordPress and I changed my site URL under general settings…

My files are housed in https://example.com/wordpress on GoDaddy’s FTP

I know how to hardcode the correct Site URL in, but I dont want to do the temporary fix.

I came across these instructions below:

Edit functions.php
If you have access to the site via FTP, then this method will help you quickly get a site back up and running, if you changed those values incorrectly.

1. FTP to the site, and get a copy of the active theme’s functions.php file. You’re going to edit it in a simple text editor (like notepad) and upload it back to the site.

2. Add these two lines to the file, immediately after the initial “<?php” line.

update_option(‘siteurl’,’https://example.com/blog&#8217;);
update_option(‘home’,’https://example.com/blog&#8217;);
Use your own URL instead of example.com, obviously.

3. Upload the file back to your site, in the same location. FileZilla offers a handy “edit file” function to do all of the above rapidly; if you can use that, do so.

4. Load the login or admin page a couple of times. The site should come back up.

HOWEVER, I can only find a admin-function.php file , which tells me to use the admin.php file as everything is redirected

I cannot find a function.php file anywhere.
It says to create one if I do not have one in the

“If there is no functions.php file in the theme:

Create a new text file called “functions.php”

But I have no clue where to create this file…

Any help would be greatly appreciated!