Download Nexus Root Toolkit 2.0.0 from here, here or here. You can download previous version of Nexus Root Toolkit 1.9.9 from here.

Unlocking, rooting, relocking and unrooting simplified! (and much more!)

VERSION 2.0.0 - This program will automatically bring together all the files you need to unlock and root your device in a few clicks, or flash it back to stock and re-lock it. You can also use this program to backup/restore all your important data, flash zips, set file permissions, push and pull files, install apps, generate logcats/bugreports, and much more! With the included file association options, you can perform tasks like flashing zips, installing apps, restoring android backup files, and flashing/booting img files with just a double click! The program includes a full featured interface for automating tasks in TWRP, enhanced restore features, an in-built auto-updater/notification system, ‘any build’ mode, advanced restore features,’NRT- Live Log’ for viewing the adb/fastboot cmds that are run in the background, quick tools utilities, and tools for taking screenshots/screen-recordings. All the latest Android builds and Nexus devices are officially supported including the new Nexus 5, with full KitKat support for all the newly upgraded devices. The program intelligently and selectively downloads the files it needs for your device and makes sure you are using the latest files available. The program can even auto-detect your device and build. This release brings Lollipop support, bug fixes and general code enhancements and optimizations.

Supported Nexus devices:
· Galaxy Nexus: GSM Models (both yakju and non-yakju builds)
· Galaxy Nexus: CDMA/LTE Verizon Models
· Galaxy Nexus: CDMA/LTE Sprint Models
· Nexus S: Worldwide, i9020t and i9023 Models
· Nexus S: 850MHz, i9020a Models
· Nexus S: Korea, m200 Models
· Nexus S 4G: d720 Models
· Nexus 7: Asus Tablet
· Nexus 7 3G: Asus Tablet
· Nexus 7 v2 (2013): Asus Tablet
· Nexus 7 v2 (2013) LTE: Asus Tablet
· Nexus 10: Samsung Tablet
· Nexus 4: LG Phone
· Nexus 5: LG Phone
· Nexus 9: HTC Wifi Tablet
· Nexus 6: Motorola Phone

Instructions:

1. Select the correct device and build (what you are currently running)

2. Configure your drivers if you haven’t already using the driver guide (If you aren’t sure use Step 3 of the driver guide to test your drivers).

3. If you need to, backup your important data.

4. Unlock your device

5. Root your device

6. Enjoy! ^_^

Learn more about each option by mousing over the control, dynamic tooltips will provide you more information, also each button displays a message about what it does first.
So the best way to get familiar with the toolkit is simply to press the buttons and read what it says.

What’s new in Nexus Root Toolkit 2.0.0: January 9th, 2015
· New dual-style intelligent ADB/FASTBOOT connectivity checking system. Now users are able to start any NRT script from either fastboot or adb mode, and the toolkit will automatically detect their device state and continue from there.
· New ‘no-force encrypt’ flash stock option for N6/N9 that will allow users to use ‘No-wipe mode’ on their previously decrypted device, and retain their decryption (and data) when upgrading.
· New ‘Manual Masterlists’ importing, so users can get the latest masterlists even if the toolkit says ‘can’t access update server’
· New feature in advanced utilities for changing/resetting your devices display density.
· Live Log now has additional starting information, to make it easier to provide support.
· Re-built the Quick Flash (file assocations *.img) interface and included the ‘cache’ and ‘vendor’ buttons.
· Extra info when setting SuperSU beta, which informs the user that beta release SuperSU’s may not always be more recent than the latest stable.
· All ‘Flash Stock + Unroot’ options moved from the toolkits settings menu to the flash stock interface.
· Text revision on main interface to show that “Flash Stock + Unroot” can be used for “Restore/Upgrade/Downgrade”.
· Fastboot flash ‘Cache’ button added to advanced utilities and new quick flash (file assocations *.img) interface.
· Quick Tools are now fully dynamic with the new intelligent connectivity checking so the user no longer has to specify if they are in adb/fastboot mode.
· APK Installation now automatically checks for special characters in the file name that could prevent installation, and if present – removes them on-the-fly, then auto-renames them back to their original name – all without user interaction.
· No-Force Encrypt flashing script (Advanced Utilities > Fastboot Flash > Boot > No-Force Encrypt) now performs both fastboot erase and format so that it works properly on n9 (which disallows the fastboot format userdata cmd due to f2fs file system).
· Determined that the ‘can’t access update server’ is related to users having download managers installed on their machine, so NRT now recommends uninstalling those (for now).
· About NRT script now displays additional text to indicate ‘beta’ SuperSU being used.
· Settings.ini is now primed with the blank sections for improved organization and readability.
· On first run if SuperSU beta has a greater version number than stable it is set as the default (can be disabled in toolkit options).
· Improved ‘Other’ factory pack recognition scripts, to better identify factory packs that are not listed in the kit.

via www.wugfresh.com