Dear aspirant

If your addhar card number have been already issued then if you lost also you can download anytime it from addhar website which is uidai.gov.in with help of your addhar no or enrollment no. And mobile number register with your addhar card. If you don't have registered mobile number then also you can download it. Please visit UIDAI website for more details. You can visit addhar center for this or any internet cafe which do work related to addhar.

In case if you don't get your addhar card,then you can carry your 12th exam admit card or 10th class passing certificate/marksheet/admit card as your valid I'd proof. This all are official documents of your educational qualification which can be used as valid I'd proof for entering examination hall.

Hope I may have resolved your query.

All the best !!