This should take between 20 to 50 minutes to finish (Depending on your internet connection speed).
First download and install the USB driver for your device. Use link above.
Then download the correct firmware file for your device. Be sure to download the correct file for your device, because you can’t use just about any firmware file for any device. Then download the odin software as well.
Copy and place all these files on your desktop, so you can easily find them. Now boot your phone/device into download mode. To achieve this (download mode), follow the steps below:
Switch off the phone completely. Now press and hold the following keys simultaneously:
Volume Key Down + Home Key + Power Key
Now the phone is in download mode. Connect the USB cable to phone, then to PC. Launch the odin software now. Make sure the following options are selected as seen in the photo below.
Click the PDA option, to browse for the firmware/flash file you downloaded for your device. This is what will be used by odin to flash your phone.
Once the flash file is uploaded, click the Start option to begin the process. Just sit and wait while your phone is flashed/upgraded. It’ll automatically reboot when done, then you can continue the process on your phone. Your phone should now boot and you can walk through the setup like any other new phone setup. That’s it. You’re done.