Why I do not receive Android updates for Samsung Galaxy Nexus GT i9250m? I have Galaxy Nexus GT-i9250m. It is currently running Android v4.1.1. I am in India. I want to know how to update my phone to v4.2 officially without rooting. I have already tried checking for updates using Settings-&gt;About phone-&gt; System Updates.

Asked similar question in gsmarena.com but to no success. Tried solution provided there to Goto Settings-> Apps-> All-> Google services and Frameworks -> Clear Data, but to no success.

Is there any way doing it manually on Galaxy Nexus i9250m without rooting the phone? Like downloading the ROM and trying to run it.
The devices which were bought from Google Play are takju and the ones from Samsung are akju. I think your phone is yakju (Google Play didn't sell  Devices in India).
Takju gets all updates directly from Google. If you want to get all updates from Google at the time of release you have to convert to takju.
How Can you do that
Please follow below to convert from yakju to takju (stock) without losing your data/apps: (assuming you know adb &amp; fastboot and have set them up on your computer. Also assuming that bootloader is unlocked) [Please read before you implement]

Download the 4.2 factory images for Takju
Extract files using 7-zip on Windows (you need to extract twice and will get the files as: bootloader-xxx.img; radio-xxx.img and image-xxx.zip)
Copy these files to the location android-sdk/platform-tools/ (if you have the android-sdk installed or to the location where adb &amp; fastboot is)
Plug in your Galaxy Nexus (ensure Debug option is enabled under Developer Settings
Follow these commands:
a. adb reboot bootloader
b. fastboot flash bootloader bootloader-xxx.img
c. fastboot reboot-bootloader
d. fastboot flash radio radio-xxx.img
e. fastboot reboot-bootloader
f. fastboot update image-xxx.zip

This would update your Galaxy Nexus from Stock 4.1.2 (yakju) to Stock 4.2 (takju) without losing any data/apps
Note:

If you are using Windows, follow this video tutorial to setup adb and fastboot
If you are on Mac, use ./ before the commands for execution

Note 2: With this method you don't need to remove the userdata.img as the command fastboot update image-xxx.zip does not touch the userdata on your device.
*Disclaimer: Tried with Unlocked Bootloader, but you follow these at your own risk.
Or you can Download factory image for yakju from here and try similar step above for just updating (without converting from Yakju to takju)