If you have registered for the KVPY then your ID and the password must have been mailed to your email id. So search in your email and you can get your ID. Now the ID for the KVPY is the application ID. SO if you have the confirmation page, then you can get the ID for the KVPY and if you forget your password then you can retrieve it by clicking on the 'Forget password option'.

To know more about KVPY preparation tips, visit the link below:

https://school.careers360.com/articles/how-to-prepare-for-kvpy

I hope this answer helps. All the very best for your future endeavors!