Can I reflash stock with kies I'm on a Samsung Galaxy s4 sgh-i337 from att and I messed up my system a little bit I want to reflash and restore stock firmware with kies. Will that work?  Also, I am rooted will kies work with me?
It should, but if it doesn't, it won't hurt to manually flash your stock firmware with Odin.

It's also worth noting that Kies sometimes has trouble recognizing devices which no longer boot up normally (speaking from experience); in which case you would be better off using Odin or Heimdall.