After moving, can´t upload anything to media library

When my site was as subdomaine it all worked fine uploading images to media library.
A while ago I moved the site so it could be up and running. I have done exactly as I did with my other site (that works fine with media library after moving it)

But this other site I just can´t upload anything to media library after moving the site. All I get is a white square with red cross.

I really hope I don´t have to reinstall it all cause the members have already written lots of stuff. Everything looked fine that´s why I didnt notice this until now when I try to upload media for the first time after I moved the site. I have not installed any new widgets after I moved the site.

I dont know a thing in coding. I´m totally new to this.
I have the latest version of WP. And theme Twenty eleven.

And as I said I did exactky the same way as when I moved my other site and that one works great!

Can I just move part of some folder that belongs to the media settings so I don´t have to reinstall it all. what shall I do?