Problem to add/retire pictures in post and portfolio slider images

Hello everybody !

I’m working on a website using Virtue theme. For the moment I’m working locally connected (using WAMP server).
All was working well but since yesterday, I’ve noticed a problem to add (or retire) pictures in post slider images and the same problem in portfolio slider images (which is a bit embarrassing for a portfolio item).
In fact, when I click on the button “Add images” in the post options section (or portfolio options) to put images in the slider, nothing happends ! WordPress doesn’t propose me to add images in the gallery by uploading medias in the media library, or choose a media in the library. I can’t add images to the slider, but I can put an image as “front-page”. And when I try to retire an image which is already in the post/portfolio slider images, clicking in the “-” symbol on the miniature, nothing happends too …

I use WooCommerce extension, because it’s a blog and e-commerce website, and I don’t have this problem to put images in my products galleries.

So, I suppose it’s a problem with Virtue, but I don’t know what’s the problem. I’ve tried to disable each extension I’ve installed but nothing has changed. I’ve also tried to disable and enable again Virtue theme, but the problem is still here !
It’s like the function called by the button “Add images” is not working. And it’s weird because 2 days ago, it worked !

Can you help me please ? Thanks for your answers.

(And sorry if I’ve made some mistakes, I’m French and everybody knows that French people are not really good at foreign languages ?? )