How to fix Microsoft SQL Server, Error: 262?

From this blog post

To add a Windows user that has the login “machinename\Administrator” to the sysadmin fixed server role

1. Log on to the computer using the credentials for the machinename\Administrator account.
2. Click the Start button, point to All Programs, click Microsoft SQL Server, and then click SQL Server Management Studio.
3. Connect to an instance of SQL Server.
4. Click Security, right-click Logins, and then click New Login.
5. In the Login name box, enter the user name.
6. In the Select a page pane, click Server Roles, select the sysadmin check box, and then click OK.

To add a Windows user that has the login “domainname \username” to the sysadmin fixed server role

1. Log on to the computer using the credentials for the domainname\username account.

2. Click the Start button, point to All Programs, click Microsoft SQL Server, right-click SQL Server Management Studio, and then click Run as administrator.

   ps: “Run As Administrator” option elevates the user permissions In the User Access Control dialog box, click Continue.

3. In SQL Server Management Studio, connect to an instance of SQL Server.
4. Click Security, right-click Logins, and then click New Login.
5. In the Login name box, enter the user name.
6. In the Select a page pane, click Server Roles, select the sysadmin check box, and then click OK.

Click Start --> All Programs --> SQL Server Management Studio Express

SQL Server Management Studio Express---> Right Click--->Run as Administrator--> Click Yes

It works