Refuses the phone to change to romanian or do you simply miss the language now after you've updated?
If the language is gone it's a case where the reseller you bought it from has added the language themselvs to the phone as it wasn't initially ment for your country ( they buy it cheaper from other countries). So when you now have updated, the phone has been updated with fw initially ment for your device, hence romanian added by the reseller is gone. You will have to visit a Nokia care point and ask if they can install the language pack which you need.
If romanian is one of the choices in your lanugage selection but nothing happens when you select it, I would first pull out the battery from the device and wait 1 min before putting it back together. I would then boot it normally. Check again, if not, try to reinstall the update. If that does not work, try a hard reset. Beware that a hard reset will wipe the phone memory so I would make a back up of everything you need first before doing that. If it still doesn't want to execute your selection, please visit a Nokia care point.
Good luck!