Try again to receive help

I am stuck. When I attempt to log in to my WP Dashboard, I get a
“Http 404 Not Found” message. My blog (www.tericbrooks.com) is up and running, but something is very wrong.

Here are some facts:

1. It is a Yahoo Small Business hosted site.
2. I have a https://ftp.tericbrooks.com file (could this be the problem)
3. I was able to log in to the dashboard just fine until about 3 days ago.
4. Today I got as far as to enter my username and password. Then the gray 404 Not found screen appeared again.
5. Usually, I CANNOT access the dashboard from https://www.tericbrooks.com/wp-admin.php
Where I do begin to solve this problem? I’m devastated, I desperately need to update.

Thanks.

Teri