SNS has gone can't be re enabled again Following this thread

http://forums.androidcentral.com/samsung-galaxy-s4/296366-facebook-log-sync-applications.html

I have disabled the SNS service

now Yahoo mail app does not notify for Facebook emails, it does notify about everything else. In status bar i got the emails but not from facebook and if i manually refresh email list i get the facebook email but no notification about it.

I tried to uninstall facebook and yahoo mail then re install them but SNS still missing from services > All

Now everytime i login to facebook i get this annoying (other type of message) Samsung galaxy would like to access your account if i add the sync it keeps asking me again each time i login. It was 
"Log in to sync Facebook with your other applications" message before disabling the SNS

What can i do please help? Been hours i am trying with no avail.
Ok so after i tried everything to recover the SNS process nothing has worked but a factory reset, however Yahoo mail still gets Facebook emails without notifications so i am guessing this is a problem at their end. I would not recommend to stop the SNS process to get rid of the message "login to sync facebook with your other applications" as you can see a small issue turned into a big one. I am using Gmail now to get Facebook emails and everything works just fine. Big thanks goes to HasH_BrowN for trying to help me out solving this issue.