Blank pages appear for posts and preview

Hello everybody,

I think I have done a wrong manipulation with my blog or while editing some files.
I cannot view my posts anymore, a blank page appears instead. Same when i want to preview a post.
The rest of the blog and the pages are all fine, see here:

I do not think it’s a plugin, because it only affects the single posts.

I assume it could be because I edited single.php? But when I put back the previous edition, it does not change anything and it’s still blank…
Should I maybe copy/paste a normal version (like a template) of the file single.php from the theme Kale 2.0? But I do not know where to find it.

I updated my theme version last week (now Kale 2.0), but all was fine.
After the update, all posts were online and working fine, it’s when I wanted to post a new post yesterday, that I could not preview it (page was blank) and then just to see, I published it… but same, it’s blank on the blog.

Hope you understand my English.

Any help would be very much appreciated.

Best,
Audrey

The page I need help with: [log in to see the link]