You probably got corrupted files on your phone. Forget about back-up and restore, this is useless because restores corrupted files, even after reintalling the firware.
First of all, try to locate the mokia.mobi on your phone browser favourites.
Once there, locate the social app, download, install and reboot.
No joy? Try the hard path:
Do not three-finger reboot, it crashes your smartphone. Instead, reset and restore. Reboot.
Reinstall the firmware. Reboot. Go to SW update and perform all updates. Reboot.
Now access MAPS and log your account there. Reboot. I don't know why MAPS are related to OVI Store, but it is, and you do not log your account there, Ovi store goes blank screen forever.
Try your Ovi Store and reinstall your Social app from there. Reboot.
It is probably working now.
WEB TV is a third party service hence not Nokia responsibility. Mine vanished after the firmware update, but there are some still at OVI STORE you can download.
If, in any moment, you did the three-finger reboot, there is no way to restore normal applications without taking your phone to Nokia Care Point.
If not, there still a small chance of your phone, somehow in its existence, crashed some QT files by installing some third party applications. So, be sure you have not installed anything outside Nokia OVI Store. If you did, nokia care point only to save it.
If it is not the issue, locate the Nokia.Mobi on your browser and install your social app from there. It is the only option you can use when OVI Store is not working. You can also reinstall OVI Store from there and your WEB TV apps.
Try it on and remember to reboot your phone on every install.
Haven't downloaded anything "unapproved" on to my phone always use OVI store. By the way Ovi store is still on my phone and still works. Everything worked for 1st couple of weeks after Anna upgrade then went iffy and Social stopped working. Web TV Apps are still on my phone but no longer load either (and can not delete them for some reason). Looking at the Feedback on the Social app on Ovi Store many people are having the same issue with Social. No Idea what a 3 finger reboot is so won't have done that.