Media Uploader doesn't load pictures

http://velesna.com/o/ - this is the site where Media upload is activated: 

http://velesna.com/o/dz-1-tsik/ - this is the page where I am trying to load and it doesn't work.

I checked and I had previous versions of both wpDiscuz and Media Uploader.

Now I upgraded it to the last version http://prntscr.com/kxdizh but it doesn't help.

So, it means that previous and current versions have the same issue on my website.

About cache plugins: actually, nothing have beed changed on my website for months already. I mean that this morning wpDiscuz and Media Uploader worked fine and now they don't while nothing have been changed at all. I don't know any cache plugin on my website and truthfully I don't know what it is.

I sent you login details on you email.

Thank you a lot!!!

Hi Astghik,

I have done no changes at all. As I explained you upper that this issue happened from time to time but this time it lasted very long time. And also nothing was changed on the website when it happened before. So, I suppose that the reason is not within the website but within the plugin or add-on. Or it can't be?

Please, tell what do you think can be the reason of this problem? It is important because I use Media Uploader for paid classes and thus I really need that it works properly.

Thank you in advance!