My admin page won't load after logging in

I just upgraded to the latest WP version. It allowed me to log in the first time I tried to do so. I added a post. But since then I cannot get to my admin panel. It seems to log me in (I get no error message), but then there is only a blank screen. The URL line reads the log in URL (i.e., it doesn’t load the admin). When I type the admin URL, that doesn’t work either — it just stays in the URL line and I get a blank screen. I’m using the twentytwelve theme. I upgraded in part because I kept getting messages like the following for my blog (dozens of times):

http://michaelsheiser.com/PaleoBabble%5D Site Lockout Notification. A host, 157.56.93.207(you can check the host at http://ip-adress.com/ip_tracer/157.56.93.207) has been locked out of the WordPress site at http://michaelsheiser.com/PaleoBabble until XYZ… etc etc.

I was thinking maybe someone was trying to hack me. I have not had a message like the above since encountering this log in / admin problem.

Lastly, I am an amateur. I don’t know how to do any code. Can anyone help me get back into my site? The location of the blog is: http://michaelsheiser.com/PaleoBabble

Thanks!