I'm doing SEO on a website (www.rancorinfotech.com) for last 7 days, though this site had duplicate content but was still ranking on first page (position 5-10) for its targeted keywords (before I started work) without having proper SEO. But today website is not showing in top 100 results, I'm confused why? Website is not banned I have checked it.

If duplicate content is the issue then why it was ranking before?
Is there any other reason for the drop ranking?
What should I do now to regain the ranking?