"Login failed for user 'sa'. The user is not associated with a trusted SQL 
Server connection." 

SQL Server Error Error: 18452

I spend quiet a loat of time to find a solution to this problem . Finally Here's 
the answer


Open
Microsoft SQL Server Management Studio Express
Login Using Windows Authentication

1. In the object explorer click on security (Expand Security)
2. click on logins (expand logins)
3. double click on sa - to open login properties window
4. click on general
5. here on the right side u can change the password for sa
6. select status
7. Settings -> Permissions to connect to datbase enegine
change to Grant
8. Settings -> Login -> Change to enable 


You need to enable sql authentication

Open Microsoft SQL Server Management Studio Express
Login Using Windows Authentication Mode

1. Right Click On SQL Instance In my case its
Murugan\SQLExpress

2. Select Properties

3. Select Security

4. Change Server Authentication to
SQL Server And Windows Authentication Mode

5. Click On OK

You are done


Now This i did several time and it still didnot work 

This is the last step you need to do. 

Start -> Control Panel ->Administrative Tools->Services

Find the serivce SQL Server
or SQL Server ( SQLEXpress) 

Double click on it 

Click On Stop 
Once the serve Stops Click on Start

Thats it u are good to go. 

In case u did not get it running. Please send me a mail with the error 
I will defanitely try to help u 

mail to :