I've been logging into my blog - backthatthingup.wordpress.com for weeks now.
Last week, I went to log in as usual, but couldn't.
I can't log in to the main wordpress.com site either.
When I try to log in, I get this message: "Please log in using your WordPress.com username instead of your email address."
It doesn't matter whether I use my username or email address. I haven't changed my password either.