Hello aravind,
Dont worry.If you don't have /lost your application details you can get it. The application number will be send as message to the registered mobile number. The application form will be downloaded once, you finish the application, so check in downloads in pc through which you have applied. 
If you don't get in the above ways: 
You can download fee payment status by 12th hallticket number and dob. In that you will get payment id and may get application number. 
I will try other possibilities..,  and comment you. 
Please comment if you don't get application is through the above process, so that I will try to  sort it out in any other way.

All the best !