Content content content..... Write some unique articles and post/ping your site. You should be back in 2 weeks or so.
I were in your situation some month ago, but Google re-indexed my site again after some days. Not even now i don't know what was that all about.
bene int he same situation, bought a domain name had decent PR, and then slowly slipped down the ranks to oblivion! If your site shows up when you search for yourname.com then you have not been banned, just continue getting backlink and keywording the site and it will bounce back.
One of my sites stopped getting indexed for months. It was a Wordpress site. I didnt write for a bit and when I came back, Google stopped slurping me. So I then waited a few months and still nothing happened. Finally I got rid of the sitemap and just started writing more than before. So 4-6 short articles a day. I mean each article is only 1-2 sentences. Anyways, Google is now feeding on my site again every few hours. Oh yeah, I also used the Webmaster Tools to find some bad links and got rid of those.