If you use a mozilla based browser (Mozilla, Firefox or Netscape Navigator), referrer sending can also be deactivated (it is activated
To change that setting, browse to about:config (copy-paste bold text to browser's address bar, then press Enter), then search for "network.http.sendRefererHeader".
If the value is set to 2, referrer sending is enabled for clicked links and images,
if the value is set to 1, referrer sending is enabled for clicked links only
and, finally, if it is set to 0, it is disabled.
To enable it, double click on it, then change the value and restart browser.
If files aren't still downloaded, browse to about:config once more
and search for "network.http.sendSecureXSiteReferrer".
If the value is set to TRUE, referrer sends normally and if it is set to FALSE, it is disabled.
To enable sending referrer, double click on parameter, then change the value to TRUE and restart browser.