When you first install Sitecore, the standard account is created with a username of “sitecore/admin” and a password of “b”. You should immediately change that password, especially if you are working on a production instance of Sitecore. If you somehow forget the password, you can update the database to restore the password back to “b”.
Sitecore uses the Microsoft .NET Membership model in the Core database. The password is stored in a one way salted-hash. There is no way to decrypt the current password. When a user enters their password in Sitecore, it is passed through the hashing algorithm and the result is compared against the value in the database. Therefore, the only solution is to run a sql query to set the salt and the hashed password in the database so that “b” will be authenticated as a password.
First, open SQL Server Management Studio and connect to the appropriate database server. Find the core database, right click and choose “New Query”. Execute the following query:
update [aspnet_Membership] set password='qOvF8m8F2IcWMvfOBjJYHmfLABc=', passwordsalt ='OM5gu45RQuJ76itRvkSPFw==' where userid in (select userid from [aspnet_Users] where username = 'sitecore\Admin')