if you have not done onpage optimization in a proper way that may be one of the reason. check the broken links check the keywords whether you have stuffed it in your content.if you have done the optimization in a proper way then waite for it . it take little bit of time to come back.
Thanks everyone, I find this so ridiculous...any off-site seo is done in sync with my other sites which are not "sandboxed"..why the heck would they do this?? I never touched the content on my site for a while. I don't think it's a competitor screwing around, the site was not too popular..we'll see in a couple of weeks.. Can someone be questioned at google for this or do they not care or bother with us? Is this an automated process by google or does someone actually analyze and remove the domain from their search engine?
if you can search for site:domain.com in google and see pages from your website, you arent banned. if you're not ranking well for competitive keywords you're in the sandbox
Checked your site also at copyscape.com if you have a duplicate content or Broken Links.... I experienced this kind of problem, when i encountered this problem i checked the broken links, duplicate contents, and Checked my Onpage if there are things that need to be changed and at that time i did not do other Link Building Stuff except Blog Reviews and the site was back to where it was....
First, check to see if your site indexed in google or not. You can use this position finder tool to check the rank of your website for your niche keywords. If you find it and it is pretty much at the bottom of the results, start working on creating unique contents, creating backlinks and check onsite optimization. If you don't find it at all, that means you have been penalized. Then, you have to wait for sometime to get out of the penalty and get on the good books with google.
Hey all, Thanks for the help and replies. My site is back in google. I never touched a thing on the site or did any seo...site disappeared for a week and came back. Interesting.....