Dear aspirant,

As you have mentioned that you have not filled up your roll number of 12th in the application form of neet.

So let me tell you that you don't need to worry about this as this is a very small mistake and if the conducting body finds any mistake in your application form then you will be intimated by sms or mail that you need to do correction in your application form and you need to correct your information and hence your application will be accepted by them.