The first question I'd ask is how long has this problem been happening?

If it's been too long to be a 2 or 3 day bug on Google's end - it could be a sign that your server's been hacked and you haven't recognized it.

I've just has a 2 year old site that's been ranking page 1 for many terms, vanish as well, yesterday it was there today it can't be found anywhere. The site's all original content, good back links etc.

Maybe it's a glitch, mine's a .co.uk.

tedster, what do you mean server's been hacked? mine is a .com - excellent original content/backlinks.

.com is your top level domain. I'm talking about your web server - the security of the actual software that hosts your site.

There is a current epidemic problem on the web created by hackers and spammers. And the techniques that these spammers and hackers are using are not easy to see. If you or a regular visitor goes to your site, all seems to be well. But when googlebot spiders, things are very different.

Here are two active discussions:

How Hacked Servers Can Hurt Your Traffic [webmasterworld.com]
Is Your Site Being Abused [webmasterworld.com]

i have a site 6 yr old started in 2003, over 8L page views every month, ranked on 2 to 10th position with most of its keyword (over 200 keywords), almost non-commercial site but using google ad. today i just saw, my site is not there. it has reached to 150 position with its main keyword, which is its name actually. Rest of the keywords are no where. Page also has been reduced. although sometime gooogle shows full 1000 results but some time only 800 results.

what could be the reason, this is one of the major site for the business and we normally dont do on this site much except adding new information pages by creating new sections, which are not keyword based at all.. last month we have got PR raise as well

Pls suggest an investigation.

Try http://www.google.com/safebrowsing/diagnostic?site=http://example.com for a malware test. Also, make sure you're not (unintentionally) hiding content form the googlebot (javascript links, etc.), as this could be perceived as cloaking.

With the risk of stating the obvious, make sure you re-check your robots.txt and your META robots tags. Finally, make sure you're not (unintentionally) linking out to bad sites. Link rot can happen to anyone, but old content is particularly vulnerable.

[edited by: Robert_Charlton at 7:53 pm (utc) on Feb. 3, 2009]
[edit reason] delinked sample diagnostic url [/edit]

For more information on the Google Safebrowsing Diagnostic Tool, see these Google pages...

Safe Browsing Diagnostic To The Rescue [googleonlinesecurity.blogspot.com]
Google Online Security Blog

Sample diagnostic report [google.com], as described on the above page.

thanks for the safe browsing tool.. it is quite clear here. no issue with content, no malware, no black-listed but it says that google did not visit site n last 90 days but i check the cache which says "It is a snapshot of the page as it appeared on 26 Jan 2009 09:36:51 GMT"

now how do i do... :-(

For the date - I'd say believe the Google cache date - or even better, believe your own server logs. It's likely that the Safe Browsing diagnostic date only represents the last time Google tested the site, and that doesn't happen with every googlebot visit.

For your ranking problem - well, looks like it's not malware. But it still may be that you are parasite hosting some very bad links, possibly cloaked to the normal browser and only visible to the googlebot user-agent. I'd try browsing the site as googlebot by using Firefox and user-agent switcher add-on set to googlebot.

i download user-agent switcher for firefox but it did not work somehow. I am also checking the all backliks to my site.

Backlick checked.. i got 3450 backlinks (most of them are from our good PR big and original content site links which are hosted on different servers and Ips) out of these 57 back links are indexed by google.com and some others and there is no bad link shown in google results as of now...

[edited by: tedster at 7:06 pm (utc) on Feb. 4, 2009]

i also got some links form the blogs which are originally written some time and also there are some good sites linked with me like orkut, world atlas, map quest and all by the author as favorite which i dont think should be a problem

Hello Tedster,

i never tried this site in webmaster tool and i just add this today and i verify this. I got to know that on last time, 26 jan when google visit my site, it generate some sitelinks for my this site as well.. But now this is no where. This is becoming very critical and wud ask you to help. what i should understand with this.. should i wait for some time..? although i have made some decent changes to the site like decreased the expertnal links, remove all JS files, although they were from the local site only..

decent changes to the site like decreased the expertnal links

How is removing external links a good thing? External links are the very lifeblood of the internet, the basis of the original Google algo. What you have done is said "I no longer want to be a good citizen of the internet, I want to hoarde my PR"

If a person suddenly became antisocial, would you expect their social standing to go up or down?

Also, if you've removed JS, have you broke anything, or increased HTML code bloat to compensate?

We dont do charity on the site, so we dont link the external (other sites) unless not useful. External link i mean, that there were some links to my sub domains from the main domain pages, i have reduced them to a genuine amount of links which i feel can be removed. As per the JS, yes i have added the HTML code and remove the js files bcoz those pages were actually having content only and no links at all (links were present in js only)