cannot access plugin directory

after installing pluginstaller i received a fatal error message
Fatal error: Cannot redeclare uninstall_plugin() (previously declared in /var/www/html/wordpress/wp-admin/includes/plugin.php:509) in /var/www/html/wordpress/wp-content/plugins/pluginstaller/uninstall.php on line 89

and can no longer access my plugin directory
mercuryfenix suggested i remove the plugininstaller app from my ftp client, which i did….i still can’t access the plugin directory page…..everything else seems to be working fine