Default I want back to 4.1.2 but konx

Hi xda

I have note 2 n7100

I update to 4.3 india rom with konx but l loss mobile network and I can't call anybody but imei is good i don't have modem file for this rom I want back to 4.1.2 because I have modem file and I can solve problem .

I want dev if could unlock konx