Unrooted : Emergency calls only after upgrade to Jelly Bean

[Shoko Katana]

A week after upgrading to Jelly Bean my phone starts to give problems. It started off with missing screen lock, then I lost internet connection. Now my phone could not lock sim card, emergency calls only and when i switch off my phone it just switch off without a box asking if i wanna reboot, switch off, turn on/off airplane mode etc. I cant do hard reset as well.
Apart from that my phone stats currently:
Network: unknown
Signal strength: -81dBm 16asu
Mobile network type: HSDPA
Service state: out of service
Mobile network state: disconnected
Imei: 3595XXXX (15 DIGITS)

The only thing I could use now is wifi. Can somebody pls help? I havent rooted my phone...

 

[Rukbat]

If it was a carrier push update (they sent it without your asking for it), bring it to them. It's their responsibility.

If you found an upgrade and put it in yourself, you can try flashing a different ROM, but there's no way of knowing what you did by flashing what may have been a bad upgrade.

 

[Shoko Katana]

I've done the upgrade through Samsung and didnt think it was a bad fix. So when you're suggesting to flash a different rom does that mean I have to root my phone? Is there any other way to revert back to my previous settings without rooting?