On your blog, Do you have search engines turned on. There is an option somewhere and you can choose if you want search engines to crawl your website.
Check whether your blog is banned or not by typing the exact URL in the search box, if it appears then it is not banned. If it is not banned then your blog is hit by panda for duplicate content or spammy backlinks. Scan your blog and clean it up... Once you are done with this ping the search engine for crawling.