First, let's point out that having a site banned from Google is a fairly r are event, reserved for particularly egregious behavior. Usually, most objectionable offenses result in a reduced search engine rank; not an outright ban. Your page may still be in Google's index, it's just no longer residing in the upper echelon of the search results.
At one time, the Google toolbar was a fairly easy and effective way to find out if you had been banned from Google: A completely gray PageRank toolbar meant that Google did not have that page listed in their index – either because the page was too new to have been indexed, or the page had been banned by Google; a completely white tool bar meant that the page was listed by Google but had almost no PageRank, or that the PageRank hadn't been calculated yet.
To a large degree, however, these guidelines are no longer reliable. The PageRank reporting, as indicated on the Google toolbar, has been inconsistent for the past several months now. PageRank updates have been taking an inordinately long time and often appear to be flatly inaccurate. Adding to the confusion are reports that banned pages are sometimes showing a white bar, sometimes gray, and sometimes even green. We're not sure whether Google is having technical issues or if Google is purposefully crippling the PageRank feature to make search engine optimization more difficult.
Whatever the case may be, we can no longer consider the PageRank feature of the Google toolbar to a reliable indicator of whether or not a page has been intentionally dropped (banned) from the Google index. Fortunately, however, there are much more effective ways to determine if your site has been removed from Google.
The easiest way to tell if your site has been banned and completely removed from Google's index is to enter the following into the Google search bar:
(replace www.yoursite.com with the domain name of the site you think may be banned)
This will show you most of the pages that Google has indexed for this domain. If this doesn't produce any results, try searching for some text – such as an address or phone number – that you are sure is unique to pages from your site and were previously indexed by Google. You could also try searching for a short piece of text. For example, to see if this page is indexed, we might search Google for the opening phrase of this article...
"Picture this: You're a successful entrepreneur running a bustling"
Be sure to include the quotation marks so that Google searches for the entire string. And, limit the phrase to Google's 10-word query limit.
If your page shows up in Google's search results, then you have not been banned. If neither searching for a unique string of text nor doing a site: search produces results, then your page/site is definitely not in Google's index.
Don't panic yet... this still doesn't necessarily mean that you've been banned by Google. There are several other causes for a site falling out of the Google index.