Q. I have a domain name and need to redelegate it, but I'm not sure who my registrar is.
A. Yo can use whois service to find that information. A good tool can be found at http://whois.domaintools.com/
Simply enter your domain name in the box provided and click "lookup". You should see some domain related information, including the registrar name. If you can't see the registar there you will need dig through your old emails.
Q. When I go to my site i get "This webpage is not available" message
A. You need to make sure that your domain hasn't expired. Go to http://whois.domaintools.com/ and lookup you domain. You should see the expiry date in the information that tool returns. Make sure that the expiry dateis some date in future.
Q. How can I check if my domain has expired?
A. See the answer above
Q. How can I verify that my domain has been properly redelegated?
A. There are lots of ways to do this. You can use utilities that come on your computer (nslookup for Windows and dig for Mac and Unix based systems) or you can use an online tools such as http://www.dnswatch.info/ and http://whois.domaintools.com/
If you're using http://www.dnswatch.info/ simply enter the domain name inside Hostname or IP box and click on Resolve. You should see something like this: