Hello Priya!

It would have been more helpful if you had mentioned the exam name. Nevertheless, looking at the details you have provided I suppose you are taking about MD/MS/MCh/DM for AIIMS institute.

If you are not abe to generate the unique code, then chances are that you application has been rejected. There are several reasons for which an application can be rejected, such as errors in application form, improper photo, not meeting the required formats etc. In that case, you wont be able to generate your code. When your application is accepted, you will receive a message confirming the same to your mobile number or email id registered. You can also check your application status by logging in using your login credentials.

To fill the form again, now new registrations are closed. So you will need to try for the next session.

If it is a different exam you are talking about, then the reasons mentioned above applies to that too. In case of query, you can contact the helpdesk of the examination authority.