How to enable the sa login in SQL Server 2008 R2?

If you don't see the 'sa' account in SQL server 2008 under security node even you have already enabled ' SQL Server and Windows Authentication mode' then Just follow the steps below to enable 'sa' login in SQL Server 2008 R2.

Method 1 - Enable the sa login by using Transact-SQL:

ALTER LOGIN sa ENABLE ;
GO
ALTER LOGIN sa WITH PASSWORD = '<enterStrongPasswordHere>' ;
GO

 

Method 2 - Enable the sa login by using Management Studio:

1. In Object Explorer, expand Security, expand Logins, right-click sa, and then click Properties.
2. On the General page, you might have to create and confirm a password for the sa login.
3. On the Status page, in the Login section, click Enabled, and then click OK.

Check out http://msdn.microsoft.com/en-us/library/ms188670.aspx for more details.

Reference: Zubair Ahmed (http://mssql-tech.blogspot.com/)