[Solved] How to Enable Mixed Mode Authentication and System Administrator (sa) Login

Take the following steps to enable mixed mode authentication on the SQL Server:

1. Open SQL Server Management Studio Express.
2. Choose Windows Authentication from the Authentication drop down list.
3. Click Connect to open the Microsoft SQL Server Management Studio Express window.
4. Right-click the SQL instance and choose Properties to open Server Properties window.
5. Click Security on the left hand side.
6. Choose SQL Server and Windows Authentication Mode on the right side.
7. Click OK to close the Server Properties window.
8. Right-click the SQL instance and choose Restart.
9. Click Yes to restart the SQL server.

Take the following steps to enable the System Administrator login:

1. Open SQL Server Management Studio.
2. Choose Windows Authentication from the Authentication drop down list.
3. Click Connect to open the Microsoft SQL Server Management Studio window.
4. Expand Security > Logins.
5. Right-click sa and click Properties.
6. Click Status and check the box for Login Enabled.

Note: You may have to give the system administrator account a password at this time as well.