[Q] Unable to root Lenovo S660 topic

I own a lenovo S660. Live in india. Have updated to the latest android 4.4.2 firmware. I have tried all one click root apps like framaroot, towelroot etc. No success.. I tried installing the rootkit su binary through recovery mode. No success either. I tried connecting to pc but pc doesnt detect my phone in adb. I tried a lot of drivers even "Koush's universal adb drivers". Nothing worked. I want to root my phone. And try custom roms. Plz help. How can i root my phone??