Kindly let this be known that after you've forgotten your login ID, the first place one looks for it is in email/SMS folder. I'll suggest you to check the email/SMS section once again & see if you had starred them. Now that you have exhausted most options of retrieving or knowing your ID, it leaves with 2 options - contact the concerned officials of KVPY & let them know about you forgetting your ID & how they could assist you or you'd have give your detail & have a new application made for your case.

Kindly check your mobile & vicinity if you can find the same & if there's nothing, kindly contact the concerned authorities.

If you get your Login ID then you can easily change your password.

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