6 months before i made a bookmarking site with cms pligg. The bookmarking site was built in another directory of my main site. After few months it was creating some problems so i deleted the directory and remove the cms too. Few days before i opened my google webmaster tools account and i was shocked to know that google is not crawling my site and showing more than 5000 404 crawl errors . What should i do to fix these crawl errors??? please help me.