I have a Galaxy S6 ... FB does not come pre-loaded. GT-I9505 running 5.0.1 For no apparent reason during the day (i.e not been a reboot) my Facebook widget (4x3) disappeared. Assume FB updated itself ... seems to do this more than any other app. And no FB widgets show in widget list. Checked that FB not installed on SD card. Removed FB, reboot, installed FB ... no difference. FB - the app is working OK, just no widgets.