Hello Manisha

Candidates who have completed Basic Registration but have not generated unique code till date will be given another opportunity to generate the code.
The facility for Generation of Code will re-open from 23rd February 2019 to 12 March 2019 (up to 5 pm)

https://www.aiimsexams.org/pdf/addendum%20No.5%20_MBBS_Jan19.pdf

Good Luck!

p { margin-bottom: 0.25cm; line-height: 120%; }a:link { }

Hiii

Sorry, but there is no option if you have missed the last date to generate the code. 17th February was last date and the authorities had given a lot of time for the code generation proces to be completed. 
From 21st febrauary, Final registration would be starting and to the best of my knowledge i dont think there would be any extension in the last date to generate the code.
You need to wait for 1 year to apply again next year.

Thanks!