Originally Posted by tmpro
No i do not have access to 4.2.1 ROM that why i was asking here to see what i could do. I thought with Odin you could flash stock firmware with out being rooted. No i do not have Knox on my phone.
You don not need to be rooted to flash with Odin but you need a ROM that can be flashed via Odin. Unless AT&T released full a 4.2.1 ROM, it's unlikely you will find one on the Internet.
If you try to flash a stock ROM using desktop Odin that includes an older bootloader, you will probably brick your phone.