Restore Google Rankings
You need to understand which algorithm has penalized your website if you are going to fix it. The Penguin algorithm which measures backlink spam was launched on April 24th 2012 and a traffic drop on that day is the best indication that Google’s Penguin algorithm is the cause of your ranking penalty. If you see a drop in traffic on or around that date, then your linking profile is the cause.
The keywords that dominate your anchor text are the ones usually hit the hardest by Penguin.