sterndata on "wordpress 4.5.2 issues"

About my website : http://sandrineboutry.com/

I just cannot upload any images anymore on my blog post I'm trying desperately to write.

Also, it's not saving anything from my post draf, and doesn't even want to center my text.

I've been trying for 3 days now to write a blogpost but everytime it's lost fight against wordpress.

I thought it could be wpml, the multisite thing that needed to be updated, but I did it today and it's still not working. I just cannot save a draft, center or work on my text to look good, and cannot include a photo (I tryed a copy paste from a word document too... still impossible to center things or insert a photo)

Please help :(