In web development, it is a best practice to reset the production password of the database whenever you are pulling it down for developers to use. When doing this in Sitecore, there is a simple procedure for resetting the Admin password back to the default password of “b” Here’s how:
The following SQL statement can be used to reset the “sitecore\admin” password to “b”:</p>
UPDATE [aspnet_Membership] SET Password='qOvF8m8F2IcWMvfOBjJYHmfLABc=' WHERE UserId IN (SELECT UserId FROM [aspnet_Users] WHERE UserName = 'sitecore\Admin')
This approach has been confirmed to work on Sitecore 6.6, 7.2, and 7.5.