I was on Google's page 1, now I'm nowhere.

Give it a few days, your site will get back to its normal position. This is normal with new sites.

This happened to my site. Our site is just under 2 years old. I almost rank 1st and 2nd position with google on my top 20 keywords. I did this with offsite optimization. Have you submitted any articles? Have you been building links? I have noticed with my site, whenever I submitt an article to 30 directories, 2 days later I drop from 3rd and 4th to 8th and 10th for a keyword. This usually lasts for 3 weeks. IMO, when you add many inbound links in a short period of time, this is a red flag to google. Google will investigate it and this hurts your rankings for a about 20 days. After your links are deemed as being quality and not artificial, then you will see yourself improve positioning for that keyword or stay where your at. Whenever my keywords jump around without my link building (not taking into consideration google updates), I know it's my competitors that are linking building. This motivates me to do more offsite optimization.

New sites usually appear among the top results ...

i agree with stevekr ... work on link building

sooner or later you will see your website peeping through in the top few pages ... a few more tweaks and you will be on top of the results

... good luck.

I encounter that one...my primary keywords rank in the first page of google however after a week it suddenly disappear in the to 100 site...they said that I only encounter a dancing keyword...so it wasn't stable right? but I wonder I did all the things to promote my keywords like directory deep link and others...still give a negative effect...