You can run this very simple SQL query on phpMyAdmin that will enable all disabled variations (always do a database backup before - Also check that your table start with wp_):
UPDATE wp_posts as p
SET p.post_status = 'publish'
WHERE p.post_status = 'private'
AND p.post_type = 'product_variation';
Or you can use this custom function that you will run once by browsing any page of your web site (always do a database backup before):
function enable_all_disabled_variations(){
global $wpdb;
return $wpdb->query("
UPDATE {$wpdb->prefix}posts as p
SET p.post_status = 'publish'
WHERE p.post_status = 'private'
AND p.post_type = 'product_variation'
");
}
// Run the function
enable_all_disabled_variations();
Code goes in functions.php file of your active child theme (or active theme). Tested and works. Once done remove this code.