There are instances where you may have set your nameserver that may not be pointing correctly on your domain to the server, which would prevent Google from crawling your site. I did this on one of my local domain, as their nameserver system is really outdated, and due to that error, Google did not want to crawl my site. Or perhaps did you temper with the robot txt? Or did you set the blog to public, and allow crawl if you are using Wordpress? You can check on these few settings.