I understand how stressful this feels with your exam tomorrow and no admit card yet. The first step is to check the official exam portal again because admit card are sometime released very close to the exam date. Also look through your registered email and SMS as many board send the admit card link or instructions there. If it still does not appear try clearing your browser cache or using a different browser to rule out technical glitches. Hit the same time contact the exam authority helpline immediately and explain your situation so they can confirm whether your admit card has been generated. If you do not receive it before the exam go to your exam centre early with your application form payment receipt and a valid photo ID because in many cases candidates are allowed to sit if they can prove registration.
It is normal to worry in this situation, but don't worry due to high traffic, the website might be slow. Or make sure you are using correct application number. And i would suggest you contact the official helpdesk.
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