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Here's a YouMoz post that was promoted to the main blog about what someone else did in this situation that may help. http://www.seomoz.org/blog/accidental-noindexation-recovery-strategy-amp-results A couple of preventative steps would have been to make the robots.txt file on the live site read-only so it couldn't have been as easily overwritten, and to use a free service like Pole Position's Code Monitor (https://polepositionweb.com/roi/codemonitor/index.php) to monitor the contents of your robots.txt file once a day and email you if there are changes. I'd also monitor your dev robots.txt, just to make sure the live site robots.txt doesn't get copied over to dev one day and your dev site gets indexed (I've had that happen!).