Login failed for user 'sa' sql server 2005 :(Microsoft SQL Server error: 18456)

Login failed for user ‘sa’. The user is not associated with a trusted SQL Server connection.(Microsoft SQL Server error: 18456):
                        Normally if the  SQL Server is not set to use both SQL Server and Windows Authentication Mode, this error will occurred. To fix this issue you have to change the Authentication Mode of the SQL server from “Windows Authentication Mode (Windows Authentication)” to “Mixed Mode (Windows Authentication and SQL Server Authentication)”.

Solution:

1.      Go to Start > Programs > Microsoft SQL Server 2005 > SQL Server Management Studio.
2.      Right-click the Server name. Select Properties > Security.
3.      Under Server Authentication, select SQL Server and Windows Authentication Mode   (refer the   screenshot below)
4.     The server must be stopped and re-started before this will take effect.