I registered a new domain and placed it as a subdomain in my hosting account, however in the domain name registrar for the nameservers I mistakenly omitted one letter in the primary and secondary name servers, I have since rectified it but however it's been a few hours and the domain name has still not resolved, and the strangest is whois on the domain name says it might be available even though I have registered it!!.

It'll take some time...check back later and it should show correctly :)