Eventuell über MySQL das Formular wieder anlegen:
INSERT INTO `s_cms_support` (`id`, `active`, `name`, `text`, `email`, `email_template`, `email_subject`, `text2`, `meta_title`, `meta_keywords`, `meta_description`, `ticket_typeID`, `isocode`, `shop_ids`) VALUES (16, 1, 'Anfrage-Formular', 'Schreiben Sie uns eine eMail.\nWir freuen uns auf Ihre Kontaktaufnahme.', 'info@example.com', 'Anfrage-Formular Shopware Demoshop\n\nAnrede: {sVars.anrede}\nVorname: {sVars.vorname}\nNachname: {sVars.nachname}\neMail: {sVars.email}\nTelefon: {sVars.telefon}\nFrage: \n{sVars.inquiry}\n\n\n', 'Anfrage-Formular Shopware', 'Ihre Anfrage wurde versendet!', '', '', '', 0, 'de', NULL);
INSERT INTO `s_cms_support_fields` (`id`, `error_msg`, `name`, `note`, `typ`, `required`, `supportID`, `label`, `class`, `value`, `added`, `position`, `ticket_task`) VALUES (69, '', 'inquiry', '', 'textarea', 1, 16, 'Anfrage', 'normal', '', '2007-11-06 03:19:08', 1, '');
INSERT INTO `s_cms_support_fields` (`id`, `error_msg`, `name`, `note`, `typ`, `required`, `supportID`, `label`, `class`, `value`, `added`, `position`, `ticket_task`) VALUES (71, '', 'nachname', '', 'text', 1, 16, 'Nachname', 'normal', '', '2007-11-06 03:17:57', 2, '');
INSERT INTO `s_cms_support_fields` (`id`, `error_msg`, `name`, `note`, `typ`, `required`, `supportID`, `label`, `class`, `value`, `added`, `position`, `ticket_task`) VALUES (72, '', 'anrede', '', 'select', 1, 16, 'Anrede', 'normal', 'Frau;Herr', '2007-11-02 03:28:48', 3, '');
INSERT INTO `s_cms_support_fields` (`id`, `error_msg`, `name`, `note`, `typ`, `required`, `supportID`, `label`, `class`, `value`, `added`, `position`, `ticket_task`) VALUES (73, '', 'telefon', '', 'text', 0, 16, 'Telefon', 'normal', '', '2007-11-06 03:18:49', 4, '');
INSERT INTO `s_cms_support_fields` (`id`, `error_msg`, `name`, `note`, `typ`, `required`, `supportID`, `label`, `class`, `value`, `added`, `position`, `ticket_task`) VALUES (74, '', 'email', '', 'text', 1, 16, 'E-Mail-Adresse', 'normal', '', '2007-11-06 03:18:36', 5, '');
INSERT INTO `s_cms_support_fields` (`id`, `error_msg`, `name`, `note`, `typ`, `required`, `supportID`, `label`, `class`, `value`, `added`, `position`, `ticket_task`) VALUES (75, '', 'vorname', '', 'text', 1, 16, 'Vorname', 'normal', '', '2007-11-06 03:17:48', 6, '');
INSERT INTO `s_cms_support_fields` (`id`, `error_msg`, `name`, `note`, `typ`, `required`, `supportID`, `label`, `class`, `value`, `added`, `position`, `ticket_task`) VALUES (122, '', 'sordernumber', '', 'hidden', 0, 16, 'Artikelnummer', 'normal', '', '2018-01-29 10:37:13', 7, '');
Oder einfach ein neues Formular bauen und in den Grundeinstellungen -> Storefront -> Artikeldetails die neue ID eintragen.