SQL Server R2 connection failure error: 18456

The solution to this problem:

First step: Enter the Database Manager in Windows Authentication mode.

Second step: In the new Explorer right-click the instance name select Properties, pop up the server Properties dialog box, we select the "Security" tab in the left column, select "SQL Server and Windows Authentication mode" and click the OK button.

Step three: Select Security in the new Explorer--login name-->sa

Fourth step: Right-click SA, select Properties: In the General tab, re-fill in the Password and confirm the password.

Fifth step: Click on the "Status" tab: Tick Grant and enable, then click the OK button.

Sixth step: Restart the SQL Server service (important)

Seventh Step: We return to the SQL Server R2 Connection Server page, authentication option to "SQL Server Authentication", password select the password just changed.

Eighth step: Click Connect to successfully connect to the database.

SQL Server R2 connection failure error: 18456