Hello Laxman!

You probably downloaded your admit card in pdf form. And then printed it out for the exam purpose. It was submitted to the invigilator because the self declaration form was also present in the admit card.

You still have the soft copy of your admit card in your device in pdf form. So, there is no problem in this regard! You can just find it your downloads, it must be saved in your device. Or try downloading the admit card again from NTA NEET official website. The link is provided below(copy and paste in your browser and fill the required details to download it again)

https://ntaneet.nic.in/ntaneet/admitcard/admitcard.html

Hope this helps:)