Everything was

Hello,

Everything was going well suddenly new images was not uploading in posts, pages, anywere.
So I follow a advice that I find in support community to try deactivate all the plugins because can be some kind a plugin conflit.
After deactivate all the site desapear and show this message:

Fatal error: Uncaught Error: Call to undefined function nocache_headers() in /export/sd210/www/jp/r/e/gmoserver/8/1/sd0442781/portalaichi.jp/wordpress-4.9.2-ja-jetpack_webfont-undernavicontrol/wp-admin/admin.php:33 Stack trace: #0 /export/sd210/www/jp/r/e/gmoserver/8/1/sd0442781/portalaichi.jp/wordpress-4.9.2-ja-jetpack_webfont-undernavicontrol/wp-admin/options-general.php(10): require_once() #1 {main} thrown in /export/sd210/www/jp/r/e/gmoserver/8/1/sd0442781/portalaichi.jp/wordpress-4.9.2-ja-jetpack_webfont-undernavicontrol/wp-admin/admin.php on line 33

Using Fillezilla I access this file and line 33 is wrote:
nocache_headers();

And I don´t know how proceed to not loose all the site.