can any one help me regarding this?
If you post the domain, we can take a closer look.
Here are some tips. My favorite fix is #3 in that list:
Hi @sahyamchakraborty, on the crypto tab if/when it says “active certificate”, can you please turn on Always use HTTPS?
Before you moved to Cloudflare, did your website have an SSL certificate? I suspect it did not and can’t support Full SSL and would have to rely on the less secure Flexible SSL.
They must have fixed it because I saw the same 404 screen as in the post.