Flashing ROMs with adb sideload Can I flash roms with adb sideload without rooting my android device ? 

I have tried installing custom recoveries once, but it didn't work. I had rooted my android device before, but due to some reason, I unrooted my device. From then, I can't root my device because, when I try to root my device with Framaroot, my phone hangs for a few seconds, and then the app just closes itself directly. I also tried to root using the Kingo Root app, but my phone just restarted several times. It was of no use. 

I am using Samsung Galaxy Core GT-I8262 running Android Jelly Bean 4.1.2.  I have tried factory resetting the device, but it was of no use. Please help me with this problem.
Flash CF-Auto-Root in downloading mode then a recovery right after. Boot into recovery and flash a new ROM, obviously make sure it is the correct ROM and correct CF-Auto-Root file before you flash it. You might want to make a backup NAND file. With my experience the rooting applications you download onto your phone such as "King Root" tend to fail more times then they succeed..