Fastest way, buy a new domain and host site on a different i.p address. Also, change wording of site significantly so other search engines won't see site as duplicate content. Then reupload and start acquiring links all over.
Yes, sadly it seems Y! can totally distroy established sites/companies at will without any recourse - this is a tragedy! When companies like Y! and Google can have so much impact on companies - they need to be regulated and held to higher standards!