restore deleted sitemap.xml in root directory

hi i accidentally deleted the contents of sitemap.xml in my server root dir. There is no sitemap.xml.gz file .i have tried rebuild wih plugin google sitemap gen 3.2.7 and 3.2.7.1 separately to no avail eventhough i updated permissions .i have wordpress 3.4.1 the file sitemap.xml remains with no content .can you help ?