hi, please try to clear the cache & cookies from facebook.com and see if this does make a difference...

i did delete all, and uninstall firefox and install it again, but nothing seems to work, + the probleme is the same when i tried chrome.

hi , you can Reseting your browsers proxi :

Open Firefox, click on "Tools" then "Options" and then on "Advanced".
 Click on the "Network" tab, and then on the "Settings" button.
 Please make sure that the "No Proxy" option is selected.

already tried that nothing changed.

in this case i'd also try to reset the hosts file on your system back to the default: https://support.microsoft.com/kb/972034

and running a scan for malware with different tools like the free version of malwarebytes & adwcleaner.

the probleme is still the same, i reseted the hosts and scaned my pc with antimalawares and found nothin and updated everything, i tried using internet explorer and it worked just fine, the probleme is with firefox and chrome.

i log into facebook using the same wifi network on my phone normally, i used a vpn software and voila it works just fine i can acces facebook on my pc.