i followed your advice and i scanned my local network with a portscanner called "Advanced Port Scanner" of Radmin.
It seems i have all port closed except for these :
i tried to run preview http mode with these ports but it doesn't work. So i tried with t1shopper.com, an online portscanner, and since now it found only these responding ports :
the main problem is still the same. I need to know what softwares close all my ports. I am not an expert about these things so i need help.