'One click install' and Plugins

when I click ‘one click install’ these text is displayed: ‘To protect your content the demo importer only works when WordPress is fresh installed. Please re-install WordPress with the default settings if you want to import the demo data.’

If I re-install wordpress, could I lose contents? and if not, how can I re-install wordpress?

also when I try to install Crystall Skull types and Visual Composer, comes this error: ‘Download failed, Forbbiden’