Resetting the SA password in Microsoft SQL Server

You cannot change the SA password in Microsoft SQL server like you do a users password.

To change the SA password you need to run the following command from a DOS prompt.
You will of course need to have some sort of SQL client installed.

C:> OSQL -E -S -dmaster -n -iC:\temp\sa.sql

where sa.sql contains

sp_password @new = 'will_never_forget_again', @loginame = 'sa'

> From http://vyaskn.tripod.com/administration_faq.htm#q9