If your site/domain is manually banned in Google (searching for your url returns no results and Google won't just reinstate it) here's how to fix it:
Set up a robots.txt file and disallow all crawling bots:
Code:
User-agent: *
Disallow: /
Now leave your site be for 5-6 months.
After such a long period Google with just remove your URL from their banned database because their crawler has been reporting the site as non-existant.
I've just got one of my domains unbanned this way. Theoretically, it should work on penalized sites too.
