Autoblog drops from 700 to 50 visitors, wtf?

I've had an autoblog running on wp robot for about 8 months now, I never touch it only use it to promote my other sites in the same niche. It has been growing steadily getting about 700 daily hits in analytics, it was also ranking for some decent keywords all on its own. About a week ago something happened to it, the stats dropped, it's not up for the keywords it used to be up for and now its getting 50-70 hits a day. I have literally touched nothing on this site, it seems it happened all on its own. Could my site have gotten sandboxed for duplicate content? Has this sort of thing happened to anyone else before? Any help would be greatly appreciated, I wanna do anything in my power to get this site back on track and growing!

Its link building time mate... it happened to me too... the sandbox thing they say...most advice here is to do link building.

xacarias is right dude, you need some "ugly" links from trusted sites ( use social bookmarking service).

ok, so what kind of link building are we talking about? a few nuke and scrapebox runs, or extensive xrumer? What were your experiences and did you manage to get your traffic back?

I have that bad time 2 months ago. I thought my site was sandboxed, so I just leave it there without do something, and after 1,5 month suddenly back to normal.