Hi @harshtiwari, glad to have you on the Netlify Support Forums. Welcome!
Fist of all if you have not visited the Netlify Support Guide link below, kindly do so as it contains troubleshooting steps to help solve the page not found problem.
If the above does not help kindly provide more information about how you deployed your site so that I can be able to properly assist you.
Also if possible you can provide a link to your repository in order for me to help with the debugging.
Let me know the outcome.
Thanks.