My sympathies for what happened.
As what n_touch mentioned, there is a need to continue your link building activity on a regular basis. Google always says go for quality instead for quantity. So I'd rather create 10 back links everyday for a month than 100 links in a day. It is important to create quality back links relevant to your website. If Google finds out that you've had a lot of 'bad' backlinks, your ranking will surely be affected.
Just keep backlinking - a few social bookmarks when adding new content, keep the links diverse by having it come from blog comments,forum profiles,social bookmarks, articles, press releases, anything you can think of just do a few of each every day and I'm sure your website will stay on the best ranking.
Thanks for sharing this here!