1/ Download Android SDK
2/ Install it to your computer
3/ Open Android SDK and download google usb-driver
Open device manager, find your N4, update driver, link it to your folder where you downloaded usb-driver and update
4/ Active debugging mode on your phone
5/ Download Kingo Android Root at: www.kingoapp.com
6/ Install it to your computer
7/ Open Kingo
8/ Connect your phone to computer
9/ Click Root
10/ Waiting about 3 mins
11/ And yes, done. Your phone is now unlocked bootloader/root
12/ Go find some custom rom for you and install it.
Simple huh??? Dont worry, i tried 10 mins ago and now my phone good to go.
PS: Important things: Your data will be wiped all, so make sure you back up all your data first.(Because i dont know that, my i lost all my data on my phone, ****tttttt.
This is a simple guide for NOOB to unlocked bootloader and root your nexus 4, just like me.