left menu disappear in appearance WP settings

Hi,

I cant access to left menu, in appearance WP settings. the left column is fixed. see my screen capture:
https://www.dropbox.com/s/svepec8oslqgt2d/Capture%20d%E2%80%99%C3%A9cran%202014-11-17%20%C3%A0%2013.56.28.png?dl=0

my configuration
# SITE_URL: https://mediators-le-niglo.fr/WordPress
# HOME_URL: https://mediators-le-niglo.fr
# IS MULTISITE : No

# THEME | VERSION : Customizr | v3.2.5
# WP VERSION : 4.0
# PERMALINK STRUCTURE : /archives/%post_id%

# ACTIVE PLUGINS :
Akismet: 3.0.3
Anti-Malware and Brute-Force Security by ELI: 3.15.16
cforms2: 14.7
Dynamic To Top: 3.4.2
Ecwid Shopping Cart: 2.6
FBF – Facebook Page Feed Widget: 1.2.1
Floating Social Media Links: 1.5.2
Google Analytics: 1.0.5
Google Language Translator: 4.0.5
Google XML Sitemaps: 4.0.8
Jetpack by WordPress.com: 3.2.1
JP Sharing: 3.2
P3 (Plugin Performance Profiler): 1.5.3.1
Product Advisor for Ecwid: 0.8 beta9
Revive Old Post (Former Tweet Old Post): 6.8.4
RSS Pages For WordPress v3+: 2.6.1
Shortcoder: 3.4
Simple Image Link: 2.2.2
UpdraftPlus – Backup/Restore: 1.9.30
WordPress SEO: 1.6.3
WP Fastest Cache: 0.8.3.0
Youtube shortcode: 1.8.5
Zopim Widget: 1.3.4

PHP Version: 5.5.13
MySQL Version:
Web Server Info: Apache

WordPress Memory Limit: 64MB
PHP Safe Mode: No
PHP Memory Limit: 256M
PHP Upload Max Size: 200M
PHP Post Max Size: 200M
PHP Upload Max Filesize: 200M
PHP Time Limit: 60
PHP Max Input Vars: 1000
PHP Arg Separator: &
PHP Allow URL File Open: Yes
WP_DEBUG: Disabled

Show On Front: page
Page On Front: Accueil (#307)
Page For Posts: Blog (#311)

thanks !!!