How to change your system administration password if you forget your SQL password?

Look, there are so many similar questions:
How to reset sa password ?
"How to change SQL password without data loss?"
"I've forgotten the sa password for SQL Server - what can I do?"
"How to Change SA Password If Forgot or Lost SQL Password?"
...

In fact, two sql password recovery solutions can help solve those problems. The simplest method is to take use of the SQL password recovery tool, and MS SQL Server Password Unlocker is highly recommended by MS SQL Server users. MS SQL Server Password Unlocker helps to decrypt the master.mdf and resets the lost MS SQL password, including changing sa password. This MS SQL password recovery program has small size yet with a powerful numeracy; it resets sa passwords of any length and complexity with no fussy settings. Just one mouse clicking to reset the selected SQL passwords.Whether or not the SQL Server is installed in advance, MS SQL Server Password Unlocker accesses to the master.mdf file directly and lists all the users to the database. For accessing the master.mdf smoothly, the password recovery program detects and stops the running SQL Services automatically.

Besides, you can also reset sa password without any program; just a few Command can work it. As following,
On the computer that is hosting the instance of MSDE to which you are connecting, open the command prompt window.
Type the following command, and then press ENTER:osql -U saAt the Password: prompt, press ENTER if your password is blank or type the current password. This connects you to the local, default instance of MSDE by using the sa account. To connect by using Windows authentication, type this command: use osql -ENote If you are using SQL Server 2005 Express, avoid using the Osql utility, and plan to modify applications that currently use the Osql feature. Use the Sqlcmd utility instead.For more information about the Sqlcmd utility, visit the following Microsoft Developer Network (MSDN) Web site:
Type the following commands, on separate lines, and then press ENTER:sp_password @old = null, @new = 'complexpwd', @loginame ='sa' go
Note Make sure that you replace "complexpwd" with the new strong password. A strong password includes alpha-numeric and special characters, and a combination of upper and lower case characters.
You will receive the following informational message, which indicates that your password was changed successfully:
Password changed.

Reference: http://blog.passwordunlocker.com/how-to-change-your-system-administration-password-if-you-forget-your-sql-password/