romanticrecollections on "404 error on wp-admin page"

I was trying to install multisite on my site. Right after updating the .htaccess and wp-config files, I clicked the "log in" link to log back in - instead I got a 404 error.

I uploaded the old versions of both files and deleted the 6 tables as instructed here. https://premium.wpmudev.org/blog/uninstall-multisite/

I still get the 404 error. I've been working my way through this list, with no luck. http://codex.wordpress.org/Login_Trouble

All plugins were tued off, since I was attempting to install multisite. My website works, minus what the plugins would be doing (shop, etc). Changing the name of the plugin file has no effect.

Tuing off the theme also had no affect. I downloaded the newest version of wordpress (I also upgraded a couple days ago before this happened), and the new copy of wp-login didn't change it.

Any ideas of what to try next? Thanks!