Parse Error Syntax Error with Content – help

Re-upload a fresh, unpacked, copy of the Twenty Eleven folder to wp-content/themes using FTP or whatever file management application your host provides.
http://ww.wp.xz.cn/extend/themes/twentyeleven

Nope. Your content is safe but if you’ve made any changes to Twenty Eleven, they will be lost.

You shouldn’t be editing the default theme. Having access to an unedited version of the theme is vital when dealing with a range of site issues. If you want to make changes, create a child theme for your changes.