A Google Webmaster Help discussion thread shows a good way to recover lost web pages using Google.
First, Googler, JohnMu, recommends you take down your website down immediately. He said, "do not let the server respond to any requests. This is important because otherwise the cached pages will be overwritten by whatever content you have online now."
Second, use the Warrick Tool, which will look at Internet Archive, Google, Live Search, and Yahoo for caches of your pages. John said, it typically takes a day or two to get your content.
Finally, when you have these files, you can restore with them.
Forum discussion at Google Webmaster Help