can't access wp-admin page

Hello,

I upgraded to 4.0.1 from 3.8.5 and now I can’t access my wp-admin page. I’ve been messing around for about four hours now, but my lack of experience and knowledge is hindering my ability to figure out how to restore access so I can update my website!

my site is https://www.kristinleeb.com, and when I try to access my /wp-admin, I get a 404 error. I’ve disabled my plugins already.