I use wordpress 3.0
yesterday , I can login in and post articles,I didnt change anyting.
Today, I input the username and password, When click submit, There is only a black page appears. I am sure theusername and password are all right,
I have reinstall the blog, But now the same question appears. Please help me.

Your blog might be compromized? If you can get to your databse, do the following:

Use phpMyAdmin to access the database then look at your WordPress database table wp_users to see what users and email addresses are on file. You should see your admin user there. Check the field for your email address and make sure it is correct and save it. Then go back to the admin login and click forgot password and the system should shoot you out a temporary password.

If you can't do that, contact your host and ask them to help you access your database.

<------------ doesn't know anything about Wordpress, but if you're accessing it through a browser.

Trying clearing your cache, reseting the browser, and/or entering safe mode (to prevent add-ons/plugins from running).

Regards, Arkinder

I often meet this lind of problom! I think you can contanct with the webmaster, or sign up again!