We missed the deadline to renew our domain hosted by freenom. Now we cannot renew it through freenom nor we can register it again since it is not available. I am curious what we can do in this case. We are not sure how to contact the company to reregister our domain, diaper.cf (email sent but no replies). Shall we just register a different domain name?
I agree. This is the Let's Encrypt Community where we discuss things about TLS certificates. Generic domain registration issues are outside of the scope of this Community I'm afraid.
Most expired domains will be put back into available state after 30 days.
They usually also offer expensive late renewals during those 30 days.
But as mentioned, this forum not an authority on anything domain renewal related.