Dear Aspirant,

I suggest you get in touch with the NTA customer support by emailing or by calling. They will hear your problem and will clear your doubt as well. Don't panic at this moment as you need to focus on your study. And currently there is a problem going on with the date and application number so right now there will be no window open for getting back the lost application number so I suggest you contact the NTA and brief them your problem. They will guide you.

The contact details:

Neetug-nta@nic.in

8076535482, 7703859909

I hope this will solve your problem

Good luck