cant install seo yoast

Hey there, Im facing a deep problem right now. the thing is, i cant install the wp seo plugin. all i did was update the plugin. and after the update the plugin is nowhere to be found. and as i try installing it, all it says
“Destination folder already exists. /home/wwwyahoo/public_html/wp-content/plugins/wordpress-seo/”

what shall i do to install the plugin? need help.