Thumbnails images missing

Hi!
After a hacking, I had to restore my  website on a new host. I used on quite old (6 months) backup to be sure it was free from any unwanted content. Now that it's clean and working, I realize the thumbnails images are missing.
But I don't know if they were missing from the very start after the restauration, or if it's my fault when i deleted all the cache yesterday (I mistakenly deleted all the cache instead of clearing the expired cache).
What can I do to force Flexicontent to regenerate all the thumbnails (without clicking on hundreds of links manually)?
Thank you for any help.

hello
you need to navigate or crawl your site, flexicontent recreate all thumbs

Sorry, but I cannot see how to do this, since the thumbnails are the one of a carousel inside a universal content module, like the one you can see at the bottom of this page, for example :  www.rouchenergies.fr/qui-sommes-nous/nos-valeurs.html
Even if I click on any of the links, it only opens the article, where the picture displays correctly (but is not managed by FC). But the thumbnails do not come back anyway.

I guess the thumbnails in the carousel I'm talking about must come from the Details section of each article, true ?
If so, the preview image seems to be missing in the admin :
 

And also, if I click on "My files", I can see the preview images are also missing here, even if we talk about one I uploaded today !? :
 

I probably have to manage something I don't remember, but what?

it realy strange because image existe ....
did you try to open item, save and check ?

Hello,
Yes, I just did, and nothing changes.

I had a look into : 
public_html/images/stories/flexicontent
and I can see the miniatures (even the one of the image I uploaded yesterday)
So it must be something with the "phpthumb" stuff which seems to be supposed to call those miniatures / thumbnails, no?

I'am also thinking: the fact that I restored the website on a new host, is it possible something has changed (like permissions or so)?

you can test your new host by upload a new image and check

All I did and all I wrote here was already on the new host.
so : pictures are there, but thumbnails are missing.

maybe you need gd or imagemagik extension (php extension) check with your host

Hi!
I just had a look at my new host, and under PHP I can see that gd and imagick are already both active.
When I inspect the missing thumbnails ont the front-end, I can see this link, for example:
www.mondomaine.fr/components/com_flexico...oe=1&q=95&zc=1&f=jpg
And if I look for this image, I can find it:
.../public_html/images/stories/flexicontent/l_image-lien-vers-galerie-photos-chauffe-eau-1280x800-min.jpg
All of this makes no sens for me, why would the thumbnail be still missing in those conditions?

hello it realy strange problem ....
www.rouchenergies.fr/images/stories/flex...eau-1280x800-min.jpg works but the problem is that phpthumb can't access to this image ...
maybe an htacess crrection ?
you can disable rezize on carrousel module and choose m image it can solve your problem
on new image uploaded thumbs works ?