Here's the stupid thing I did: I deleted many folders inside the icon folder, with root privileges, and now some icons are gone, but not the main ones, the ones from compiz for instance, or some from top notification bar, like the skype one. I looked for days to find a solution to restore the icons folder, or to find the default Ubuntu icons to put them back to the folder, but I have found none.
I use Ubuntu Tweak Tool to switch between themes, icons, or cursors, and it works perfectly, but no theme or icon pack seems to bring back some of the icons like I mentioned before.
I hope there is a way to reinstall ubuntu default icon packs. Thanks in advance ;)
Unfortunately, applications like compiz usually install their own icons. You can install these icons by re-installing the application to replace the missing files.
That should work if the files are missing, however, if it doesn't, you can download the application and manually replace the files like so:
I solved it: Downloaded the ubuntu 14.04 iso. Mounted it with VirtualBox, used root to go to the icons folder, archive it, uploaded it to the internet. Then downloaded it to my OS, and just copied it to the 'shared' folder. Basically I restored the icons folder by copying it from the ubuntu iso file. ;)
You can download an unzip in the :
/usr/share/icons
download default icons from here:
http://4uploader.com/dl/257/icons.7z