Recovering The GRUB 2 Boot Loader To Protect Your Previously Installed Operating Systems

Hi To All The Mindbenders,
As Like My Earlier Tutorials i'm not Going To Consume your important time. I am Always here to provide all The Mindbenders readers a Quick and Easy Solutions.
i already posted a tutorial about Recovering Grub2 but That Was Too Advance To Learn Recovering Grub2.
Grub is similar to boot-manager(Bootmgr) of windows.
But i'm a Linux Lover And Proudly Help Someone Who wants To Stay With Linux Distros.

Now We Are Looking Forward To This Post.

Note:- 1. only commands(text) in red must be typed in your terminal.
           2. Text in green after ===> sign indicates the uses of commands you are using at that  
               instant.
           3. sda5 is my partition having Linux OS, so Don't Behave Like Monkeys Use step 1 to  
               identify your Linux Partition Generally it is In Form Of Ext4 or Ext3 or something like 
               these Formats and for your Convenience Command will show you Linux in front of   
               your Partition.
          4. Refer To My Video For Better Results.

Steps To Follow:-

Step 0.
Boot from live Linux or backtrack 5 flash drive or any boot-able media of your choice, it could be your Dvd.

Step1.
Figure out where you need to install grub 2 means we need to identify our Partition having Linux.

root@bt:~# sudo fdisk -l               =================> List All Partition
root@bt:~# ls                                 =================> List All the Files/folders of your  
                                                                                                  current mounted partition having root  
                                                                                                  Privellages                                         

Step2.
Mount the Partition where you need to install the grub2

root@bt:~# sudo mount /dev/sda5 /mnt          ========> here sda5 is the partition where linux  
                                                                                                  is and we mounted in mnt folder

root@bt:~# mount                          ================> List all the mounted partitions

Step3.
Mount the Partition to an alternate location

root@bt:~# sudo mount /dev/sda5 /mnt/boot

Step4.
Create an unbreakable link from /dev folder on the live image you booted from to the /dev folder on the partition you mounted to /mnt

root@bt:~# sudo mount --bind /dev /mnt/dev/

Step 5.
CHROOT from the live image's root to the mounted partition's root
chroot temporarly changes the root of the filesystem directory.

root@bt:~# pwd                             ================> Print Working Directory To Check  
                                                                                                The Current Root Privellages 

root@bt:~# sudo chroot /mnt

root@bt:~# sudo mount               ================> List All The Mounted Partitions 

root@bt:~# pwd

root@bt:~# ls                                 =================> List All the Files/folders of your  
                                                                                                  current mounted partition having root  
                                                                                                  Privellages                                      

if yoou found your linux hard drive content then you are almost on track 

Step 6. 
Now Reinstall the grub2 loader to the drive on which exists the partition you mounted previously.

root@bt:~# sudo grub-install /dev/sda      ==========> Install Grub In Your Hard Drive 
                                                                                                Which is sda your primary hard drive.

root@bt:~# pwd

now exit your chroot shell

root@bt:~# exit

Step7.

cleanly unmount all the partitions you previously mounted

root@bt:~# sudo umount /mnt/dev
root@bt:~# sudo umount /mnt/boot
root@bt:~# sudo umount /mnt


now reboot...

root@bt:~# sudo reboot

pull out your live flash disk

when Linux or backtrack says to login simply login and do not try to type startx in case of backtrack Use below Command Before typing startx.
And for other linux, Login To System and then open terminal then use commands.

root@bt:~# os-prober

root@bt:~# update-grub

root@bt:~# startx                =================> Only For Backtrack Linux                                         

Story Behind The Tutorial:-

I know how much it hurts when you Wants to upgrade but instead of that You Got Problems Like Previously installed linux or any other os is missing from your boot and i got the same situations when i was upgraded to Windows 7 to windows 8 Rtm. i was shocked when i rebooted my Laptop and didn't find my previously installed backtrack 5 grub menu, i can't tell you how much sad i was at that time then i asked everyone But i had a Huge List Of No Hahah. And Finally Referred to some Linux Forums And Found the Fix... Then I Recorded a video of fixing the same in ubuntu...