On January 19th, there was a page layout algorithm change. More details here:

Official Google Webmaster Central Blog: Page layout algorithm improvement

Pages With Too Many Ads "Above The Fold" Now Penalized By Google's "Page Layout" Algorithm

Suzanne

I highly doubt you've been hit by the new algorithm update, mainly because you say this happened last week. It's probably a Google dance as we call it these days, don't worry and wait - don't stop building backlinks!

Just wait it out, it happens to almost every website - especially those that are new.

That can just be attributed to google dance. Keep building quality backlinks to it and you should be in good shape.

I personally haven't seen any of my sites drop off the first page, but I've seen a few posts with guys complaining, so guessing some change was made.

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The only ones that really have to hurt from this update are the ones that are copying content and other things.

Check status and discuss on google webmaster.

You asked if there were any recent changes, so I was just pointing out the latest one. :-)

One way to check if a particular update effected you is to check whether only your Google organic search traffic dropped. If other things dropped (Bing, Yahoo, referral traffic, etc.), then it could be a problem with your site itself.

Keep in mind, your problem could be just a normal algorithm change; sites drop and rise in the SERPs. Or it could be that your backlinks (if you have any) were deemed less valuable, so it caused your site to drop.

Hope that helps,

Suzanne

As today i have experienced that there is no any particular time for seeing results up or down. As today i have found my one site pr increase without having any algorithm changes or without any updation. And as matter for the keyword then i did not have find any kind of algorithm updation in google for providing results. might be lack of your effort or due to not concentrate on that keyword after better position. So need is for the continuous effort though having good results and then only can stick to that position or get better else we have to face drop in results.

Possibly Google Dance. Wait it out.

Definitely it's Google Dance. To bring your site back fast make sure you build some quality links. Now a days sites are dancing more. I heard this from so many of my friends.

its probably what they call google dance? did your alexa ranking went down too?

Temporary ups and downs in ranks could happen to all websites and in competitive niches, they often so much and in most cases there is nothing to worry about, as long as original contents appear on sites and the existing packs of links have remained with no changes online. If your website has been operating online for less than six month, you just need to remain patient because your main positions have not still got fixed and it takes some time before seeing fixed placements.

You are recommended to add contents to your website on a constant basis and keep gathering good links for that. It's just the matter of time and as mentioned, all sites experience ups and downs in ranks, even the ones which already have been on front pages of Google for their targeted keywords. Do not forget to check contents which appear on your website, make sure they are original because duplicate contents can shake rankings in most cases, even the older domains.

I heard there was a change in algorithm on Google on last 19th. However, I would suggest you to go ahead with some more backlinks - constant backlinks for few weeks, should give your rank back