wp-admin does not work, cannot access to dashboard

Hello,

I am running a WP blog for almost 8 months. Recently, at /wp-admin page, another promp different than WP appears. It only asks me to enter password, which is different from my own WP password.

<pre align=center><form method=post>Password: <input type=password name=pass><input type=submit value='>>'></form></pre>

is the wp-admin page source. I also cannot access my dashboard from wp-login.php since it constantly directs me to wp-admin page.

On the server, I have found several files which should not be there.

[ Moderator note: malware code deleted, please do not post that here ]

There were two other files and along with these I deleted 4 of such files from server but I still cannot access the website.

http://www.kimyablog.com

is the url of my blog.