backup install failed, now site is down. all pages say fatal error

tried to install backup and it failed to install. site is now down. here is what the page says

Fatal error: require_once(): Failed opening required '/home3/floridag/public_html/generatorlink.com/wp-content/plugins/backup-wp/SnapshotDestinationDropbox.php' (include_path='.:disappointed:opt/php54/lib/php') in /home3/floridag/public_html/generatorlink.com/wp-content/plugins/backup-wp/backup-wordpress.php on line 23

what can I do?