Nexus S,Galaxy Nexus,Nexus 5, Nexus 7 ALL Variant

Here are the list of things you can do from this Nexus guide.

0. Setting up Your PC
1. Unlock Bootloader Note: Will wipe all data
2. Factory restore Android
3. Flash Custom Recovery
4. Root
5. Lock Bootloader Note: Will wipe all data

Warning:
I take no responsponsibilty
unlocking bootloader and factory restore will wipe all data SO TAKE BACKUP OF ALL DATA


Setting up your PC

Java runtime must b installed Download here:Download Free Java Software

Download here Android SDK | Android Developers

Remember the destination folder: "C:\Users\[User Name]\AppData\Local\Android\android-sdk"
Run Android SDK Manager after install
Check Android SDK tools, Android SDK platform-tools and Google USB Driver as below image
Uncheck any other checked packages
click Install
Accept both license agreement. Install



Install USB Drivers in PC:

You need to properly install the USB drivers so that your PC can talk to your Nexus device.
b.1) Power off your Nexus device
b.2) Connect Your Nexus with Computer using USB cable.
b.3) Boot into fastboot mode by holding down both Volume Up and Power buttons together



b.4) Open Device Manager and you might see some thing like this



Right Click and click "Update device Software"
Click "Browse your Computer for driver Software"
Click "Let me Pick from a list of device drivers on my Computer"
Click Next, for the device list shown.
Click "Have a Disk" button
Go to "C:\Users\[User Name]\AppData\Local\Android\android-sdk\extras\google\usb_driver"
select "android_winusb" and click OK
Select "Android ADB Interface" and click Next. It will give you a warning. click OK and Install.

If you dont see the warning like before in device manager your PC is setup

Code:
Before we go to next step. Lets open CMD we will be using command prompt for the rest of the steps.
Open CMD and type
cd C:\Users\[User Name]\AppData\Local\Android\android-sdk\platform-tools
Enter

1. Unlock Bootloader: Warning: will wipe all data

Code:
a) To Unlock BootLoader Type this in cmd promt above with out quotes
"fastboot oem unlock"
b) Hit the Volume Up button once(Will select "YES") and then the Power button(To CONFIRM) to unlock your Nexus Devices.

Feeling geek?? You are now a Geek!!! DONOT Close the Command Promt Just yet.


2. Factory Restore Android:

Download Nexus Factory image from Google https://developers.google.com/android/nexus/images

Download the latest for your Nexus Device/Android OS. I recommend the latest factory Image for your device.

a) Once downloaded. Right click the file and extract the tgz file using winrar or winzip.

b) In the extracted file you will see many file Move all of the extracted files to platform-tools folder("C:\Users\[User Name]\AppData\Local\Android\android-sdk\platform-tools ") except these two files flash-all.sh and flash-base.sh

c) Now open flash-all.sh file in word document. Notepad seem to display it weird.

you will see some comments and at the end you will see something like below.
The below is for Galaxy Nexus GSM. It will be different for other devices. Check the file.
Remove Sleep 5 from those codes. we dont need it.

ONLY FOR Galaxy Nexus GSM. See the downloaded file for your device

Code:
fastboot flash bootloader bootloader-maguro-primelc03.img
fastboot reboot-bootloader

fastboot flash radio radio-maguro-i9250xxlf1.img
fastboot reboot-bootloader

fastboot -w update image-yakju-jro03c.zip
Copy each line one by one in the order given in file and run in the Command prompt we opened previously.

DONE!! We just Factory restored the Nexus.

3. Flash Custom Recovery: (If you dont need to Root Skip step 3 and 4)

Code:
a) Download clockwork recovery from here. Search for your device and download recovery ClockworkMod ROM Manager - Recoveries

b) Place the recovery file in SDK folder.

c) Run this to flash recovery
fastboot flash recovery [clockwork recovery filename].img


4. Root: You need to do step 3 to root

Code:
a) Download root from official superuser website here Superuser ARM devices (2.0 – 4.1) or any future devices current version is 3.1.3.

b) Place the superuser zip file in your devices SD card by booting up ur device. Enable USB when it popsup.

c) Shut down Nexus and Boot into fastboot mode by holding down both Volume Up and Power buttons together.

d) select recovery by using Voulme Up/Down button in your device and click Power button to select recovery.

e) In ClockWorkMod recovery select
Install zip from sdcard-->choose zip from sdcard-->[navigate to the superuser zip file]-->Click Power button. and then select Yes and Power button when prompted.

DONE! You are rooted.


5) Lock Bootloader

Code:
If you skipped step 3 and 4 and wanted to have a pure stock just like you bought from the store. do this.

run this command in command prompt.
fastboot oem lock

DONE!