My cliente used qtranslate plugin on her website, but it was deserted by its creator and it's obsolete now.
I deleted it, and cleaned my database (with this https://gist.github.com/frnhr/4219792#file-qtranslate_cleanup-sql) but pages are always blank... I really don't know what to do to recover her content...
The website is here : http://prouchet-dalla-costa.fr/
Thanks :)
Looking at the site, it stops at this line in page source:
<div id="header-lang-icons">
This tells me your header.php might call a qTranslate function to show language flags, but since the plugin is gone and function doesn't exist, so it causes the PHP syntax error.
Go to header.php and then locate and remove that qTranslate function. The functions for qTranslate start with qtrans word.
By the way, there is a replacement for qTranslate named qTranslate-X if you ever want to switch back.