Getting 404 error message and not able to access my admin dashboard

I logged into my WordPress site as the admin and I see one of my webpages with a 404 error message. I am not able to access the admin dashboard and tried log out and log back in and same issue. When I look at the published website outside of WordPress, the website is okay. My web host is Host Gator. I’m a first time user with WordPress and everything was going fine for a month until today. I’m learning as I go along and would appreciate help in a simple way. Thank you.