Recovering Ubuntu After Installing Windows

This option will use the Desktop/Live CD to install Grub into your MBR (Master Boot Record). This option will overwrite your Windows Boot Loader
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1. Boot the Desktop/Live CD. (Use Ubuntu 8.04 or later)

2. Open a terminal (Applications -> Accessories -> Terminal)

3. Start grub as root with the following command :

• sudo grub

4. You will get a grub prompt (see below) which we will use to find the root partition and install grub to the MBR (hd0,0)

•          [ Minimal BASH-like line editing is supported.   For
        the   first   word,  TAB  lists  possible  command
        completions.  Anywhere else TAB lists the possible
        completions of a device/filename. ]
  
  grub>

  Type the following and press enter:

  find /boot/grub/stage1

  If you get "Error 15: File not found", try the following:

  find /grub/stage1

  Using this information, set the root device (fill in X,Y with whatever the find command returned):

  grub> root (hdX,Y)

  Install Grub:

  grub> setup (hd0)

  Exit Grub:

  grub> quit

• # reboot
  

5. Reboot (to hard drive). Grub should be installed and both Ubuntu and Windows should have been automatically detected.


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If after installing grub, Windows will not boot you may need to edit /boot/grub/menu.lst

• # vim /boot/grub/menu.lst

  ###################################################################################

  Restoring GRUB
   
  1. Boot from a Live CD, like  Ubuntu Desktop, or similar. It is recommended to use Ubuntu 9.04 or  newer as this has NTFS write support. 
  2. Open a  Terminal. Open a root terminal (For non-Ubuntu live CDs type su  the terminal. For Ubuntu based distros run sudo -i) Enter root  passwords as necessary. 
  3. Type grub  which makes a GRUB prompt appear. 
  4. Type find /boot/grub/stage1.  You'll get a response like "(hd0)" or in my case "(hd0,3)". Use the  output from this command for the following commands.  
  Note: 
  You should have mounted the partition which has your  Linux system before typing this command. (e.g. In Knoppix Live CD  partitions are shown on the desktop but they're not mounted until you  double-click on them or mount them manually) 
  5. Type root (hd0,3) note the space between  root and (hd0,3). 
  6. Type setup (hd0,3)  into the prompt. This is key. Other instructions say to use "(hd0)",  and that's fine if you want to write GRUB to the MBR. If you want to  write it to your Linux root partition, then you want the number after  the comma, such as "(hd0,3)". 
  7. Type quit  
  8. At this stage you can  either restart the system and install your own bootloader, or you can  continue and tell the Windows bootloader where to find GRUB which will  handle booting Linux.