My site (http://www.optionstradingexamples.com) has been fallen in Google Sandbox without announcement until I couldn't find it in any keyword search even domain name, except its url. I don't know what I did wrong and how long this takes. The traffic is down but I don't know how to save it. Please, I need your advices!!

Actually, if you site is not qualified to be shown in search engines then it is put to SandBox thats it.

When new site, for gaining higher page rank, make link building blindly. than Google put it into sand box.

Most newly launched websites are going to experience the Sandbox effect or filter which is a temporary block for websites so that they may not be able to get to the first page of Google for their targeted terms very fast.

Of course issues like how websites are promoted, their contents stats plus linking structures too may have roles to play in here. It is generally believed that the more competitive terms selected the longer period of time need to wait over getting out of filter.

Do you know how long it takes???

Noone knows the rules, but as far as I know, the sandbox effect is produced both by lack of incoming links and low quality content and also by penalizations. All of these factors can be fixed.

Google Sandbox applied when Google thinks that your site is not worthy to show up in search engines thats why it is put in sand box for a limited period to improve your site.

You might have not got that much page rank in order to show your website on SERPs. This might be due to lack of promotion of your site.You must get inbound links to your site by doing offpage optimization(article/blog/guest post submission,submission of your website in business directories etc).The more you get inbound links to your site,the more will be you page rank