Wordpress category/ tags disappeared

Hello,

My WordPress website suddenly Category & Tags disappeared. I’m looking for solution on google and it seems the mysql error.

http://www.eleventhmedia.com/blog/wordpress/wordpress-category-tags-disappeared-how-to-fix-missing-categories/

http://ycsoftware.net/wordpress-categories-mysteriously-disappeared/

I think this is caused Mysql temp directory was full so we have to empty it, then everything will came back.

I'm not expert in this case, so could you please teach me step by step how to solve this issue?

Thank you,
Tuan.

My URL: http://www.technologymag.net/vi