Stock firmwares are important when you want to roll back to the factory state. One scenario is when you have to use the phone’s warranty, which gets voided when you root your Note II, install custom CWM or a custom ROM like this on your phone. Follow the below given steps to download and install the stock ROM on your Samsung Galaxy Note 2.
1) First, make sure you have Samsung Kies or Samsung USB Drivers (link) installed.
2) Download Odin (link) on your PC and check “Auto Reboot, and F. Reset Time” in the app.
3) Download the firmware from here and extract it
4) Check PDA in ODIN app and point to ROM file you have extracted.
5) Now, switch it off; put your Galaxy Note 2 in download mode and connect the phone to PC via USB cable.
6) Click on Start button in ODIN. Green color Pass will be shown on screen if the file was successfully pushed to the phone.
7) Disconnect.
You have successfully downloaded and install the stock ROM on your Galaxy Note 2. Pat yourself on your shoulder.