@Akash97 You could just use my previous responses above to debug your form.
For example, I check your site and I have exactly the same first question…
Did you Enable Form Detection for the site?
https://docs.netlify.com/forms/setup/#enable-form-detection
One you do you need to ensure you redeploy.
If you still encounter issues you can run through this Support Guide:
https://answers.netlify.com/t/support-guide-form-problems-form-debugging-404-when-submitting/92