Hello aspirant
Dont be panick , as you have not mentioned whether you are talking about jee main admit card or neet  admit card it is difficult to assist you with proper details but taking dates of jee main examination in account you must be probably talking about jee mains .
You can get your admit card by visiting on this link here (https://testservices.nic.in/JEEMAINADMITCARD/DownloadAdmitCard/AuthCand.aspx) .
Visit the website-

Fill you application number and date of birth you can download your admit card if you had paid fee and undertaking form.
Please re check your application and dob twice for confirmation.

If you still cannot download admit card write a mail to nta raising your issue.
jeemain@nta.ac.in

Hope this will help you

Best of luck

Hello,

Do not worry and relax. You have not mentioned the exam you are enquiring about. If you can let us know the exam you are query is about we will be able to help you better. NTA conducts various exams. You application number is that one which you get after your complete the registration. Please check your email or messages in phone for the application number and double check if you are entering the correct details as per the records.