Locked Out Please Help

Hello,

I’ve scoured the forum and cannot find anything that solves this problem.
I am new to wordpress. I have been working on my website non-stop for the past 4 days and I think I might have lost all of my hard work.
I cannot navigate to my wordpress admin site.

I was having problems with a broken link to my homepage. It was routing to an error message page, instead of my sitename homepage.

I went to the settings section and changed one of the boxes which displays the way the domain name is displayed.

Upon refreshing the homepage, it immediately dropped all of the formatting from the theme I had been using.
On the admin site I hit Cmd Z (I’m using a Mac) and restored all of the original settings for that page.
I refreshed my webpage again, but it corrected nothing. I then clicked on the tools section of the admin site, but instead of going there that page became my webpage with the dropped formatting.

The content looks like it is all still there, but the formatting and theme is completely gone. All of the pictures and texts are now just laid out linearly on a plain white background.

I can navigate to an admin login page by entering my sitename.com/wp-login.php
The formatting on this is off as well. I can enter my username and password, but upon hitting the Log in button it just takes me to my unformatted homepage.

Why can’t I log in to my admin site and where did all of my formatting go?
I can provide more details as needed. ANY help in this matter would be greatly appreciated.
Thank you