The time is going to come when you forget the Administrator password for one of your sites. Or you might be unlucky enough to have your site hacked and the password changed. Now although there is no method to reset the password using Joomla via the web, there are a couple of methods you can try.
Firstly, if you have simply forgotten your username or password, you can have this sent to your email. If you use the registration feature of Joomla, simply go to the "forgotten password" page. Even if you're not using this feature, you can access the page by adding the following code to your URL:
Forgot username: index.php?option=com_user&view=remind
Forgot password: index.php?option=com_user&view=reset
For example, if your domain name is www.joomlavideodemo.com, and you have forgotten your password, you would enter:
Enter your email address into the box on the resulting page and click the Submit button. Now of course, this only helps if you have access to the email address that is linked to the account name you entered.
In most cases, you don't have access to this address in which case you need to make the change directly in the database. This is relatively easy but a little complicated to explain so have a look at the below.