U must to reinstall manually an original firmware. It is simple, without writing all the guide in this post, this is the link with all the informations u need:
http/forum.xda-developers.com/showthread.php?t=2365701
This procedure will delete all your personal data, in particular the "Part 5: Resetting and finishing". The guide says that this part is necessary, but i personally think it is not. In any case after Part 4 the phone will reboot, so check if all is right, if something crashes or isn't like it should, shutdown the phone and follow the Part 5. It is my suggestion.
Good luck