Did you self-host your blog or did you use wordpress.com and redirected the domain?
If it self-hosted, you should contact your hoster and see what they can do for you. I have to say, sometimes they delete all files and databases if a contract is not renewed.
If you used wordpress.com, you should be able to restore your blog with them and ask your domain registrar if you can re-register the domain.
I recall having read about a quarantaine period for .com domain during which nobody else but you can register the domain, but I’m not sure.
Jeroen
