There is no requirement for a site to produce a sitemap even if it is recommended. If your site is well constructed and all pages can be found via internal links then your site will work just fine without one.
I know that does not answer your question but in all honesty, you have other major problems with your site that you should be more focused on.
Please take a look at this link to see some of the technical SEO issues
https://gtmetrix.com/reports/www.cybersecasia.net/dhPUawA6/