I have too forgot it and I could not find it in my mail.....

Dear Manju, AIIMS authorities will reopen the process of code generation from February 23rd. It will be open until March 12th, 5.00pm IST. So you can generate the code again during this time. The generated code will be sent to your Registered Email and Mibile no#. Please utilise this chance and save the code. Then proceed with the final registration process like making a payment and selecting the exam city. Also take a print of the final copy of the application.