I used K to write article on my website blog www.transgateslimo.com/blog, and today I discover that the menu bar is missing on the article

I mean by the menu toolbar, the area where you can make words bold, Italic, underline, different colors, and insert "read more" and insert links, choose different fonts, or size etc....

Can you please help me to get the menu toolbar back

This comes from the editor. Check that you haven't unpublish any Editor plugins or changed the editor for your user specifically through the User manager.
Also which editor do you use?