404 after logging into http://www.site.com/wp-admin

When attempting to login at my site at http://www.lucasmcdonnell.com/wp-admin, the page looks like it’s going to redirect me to the admin interface, but then instead goes to a 404. I’ve tried logging into my other blogs from this laptop, without issue. I’ve cleared browser cookies and cache to no avail.

I’ve deleted both the wp-admin folder and wp-login file and re-uploaded them to the server, also to no avail. Logging in definitely worked a few days ago, and I have made no changes to the site or its configuration since then — it just seems to have stopped working.

I would really appreciate any help or advice with this, I’m not really sure what to try next. Thanks in advance.