Question : Need to change the default Administrator password in a SQL 2005 database

I'm not very savvy with SQL. All I know is that penetration testing has revealed there is a database instance on a specific machine in my network that is running SQL with the default password for the default account. I tried to change this before, and it appeared to be successful but I was unable to log in as admin with the password I had changed it to.

I apologize if I did not provide enough information. Any assistance would be greatly appreciated.
Thank you.

Answer : Need to change the default Administrator password in a SQL 2005 database

1)
Use SQL Server Management Studio, connect with
windows-Authentication to the server/instance
Under Security/Login,  right-click on "sa", select "properties" and then you can change the password.

2)

USE [master]
GO
ALTER LOGIN [sa] WITH DEFAULT_DATABASE=[master],
DEFAULT_LANGUAGE=[us_english], CHECK_EXPIRATION=ON, CHECK_POLICY=ON
GO
USE [master]
GO
ALTER LOGIN [sa] WITH PASSWORD=N'blah' MUST_CHANGE
GO

3)
From a command shell (start > run > cmd)
    OSQL -S <YOUR_SERVERNAME_GOES_HERE> -E
    1> EXEC sp_password NULL, 'blah', 'sa'
    2> GO