if you have previous backups you can restore it from your backups, or if you dont have any backups you can tell ur hosting privider to backups ur site for u to the most close date, i do that when i lose any configuration of my site they back up and restore mi site, its just an idea ;)

@Zia
Did you update manually platform?

Yes. I use update manually platform. Any solution Addenster?

Would you give your site URL? Also, would you describe how exactly did you update your core?

[a href="http://www.mysosial.com"]. Thanks you Addenster. :)

Got it. You need to update newsfeed plugin. Please, wait a few for autoupdate request in your admin panel for newsfeed and update it.

Thank you addenster. :)

Problem was solve. The solution is:
1) Reinstall platform core
2) If you use newsfeed 3399, please upgrade to newsfeed 3484.

Nice :)
But why did you reinstall core?