If your webmin account is locked out due to too many wrong attempts, then simply wait at least 10-15 minutes, or issue following commands to login quickly.
If you are unable to login with the root id on webmin
cd /usr/share/webmin ./changepass.pl /etc/webmin/ root newrootpassword
WEBMIN installation in Ubuntu using apt-get
I assumed that you have installed and configure your Linux box (preferably Ubuntu, but any flavor can do the job, this is the main quality of Linux OS :)~ To install Webmin , first add its repositories to sources.list, to do this first open sources.list
Now paste the following lines in the end of this file.
deb http://download.webmin.com/download/repository sarge contrib deb http://webmin.mirror.somersettechsolutions.co.uk/repository sarge contrib deb http://archive.canonical.com/ lucid partner
Save & Exit.
Now update apt-get and install webmin using
apt-get update apt-get install webmin
It will take some time to install webmin depend on your internet connection (usually less then 10 minutes) , afterward you can access it using
(TIP: you can change the webmin port by editing in /etc/webmin/miniserv.conf and change the port number to any port you like, for example 443 or 1234)