Sorry, have no intention to get attention to my problem. It was first time to use WP forum and not familiar with the functions.
My hosting is WA . The website is back to normal when i followed the instruction of Site Support from WA to deactivate the “custom sidebars”. But when i reactivated the plugin, the problem was back again. I wonder that may be caused by my customization via siteorgin CSS plugin?
Anyway i have changed to another theme (from Tish2 to Astra) and have no problem. Thank you!