Use SamMobile to download the latest firmware for your specific model (region doesn't matter) or if you want really fast download speeds use the SamFirm program from XDA. Then follow a guide on how to Odin flash your device. There are plenty of these online. I highly recommend downloading Odin from someone who shared links on XDA as there are occasionally shady scam sites with Trojan-infested versions (there is no OFFICIAL Odin site as Odin is an internal Samsung tool that just happens to be leaking out of repair shops).