Default [Q] Reinstall operating system on Lenovo A630

Hello. Recently I bought a Lenovo A630 (Android 4.0.4) from minideal. The phone was rooted by them. Yesterday I accidentally uninstalled a system application with Titanium Backup and now the phone doesn't work. Is there a way to reinstall the operating system (including root)? Any costum stable rom would be good too. Any suggestions?