A common problem many users face after installing either Linux or Windows on a system when the other is already present is an override of the default boootloader. Without a bootloader, the system is clueless about where to get boot data from. In such a case, you can try these simple steps to restore your grub menu with all the Operating Systems present in the list.

• Boot from Ubuntu 9.10 or any Ubuntu 9.10 derivative live CD ( the CD from which you installed Ubuntu).


• After the boot is complete, press alt+F2 to open a terminal.


• Enter the command fdisk as
  

  sudo fdisk -l

  This lists all the partitions as shown.


• Mount the drive marked as Linux under System ( the last column) using the command
  

  sudo mount “device” /mnt

  
  Replace “path” with the corresponding device ID under the Device Boot section. So, for the given screen-shot,
  my command will be
  

  sudo mount /dev/sda12 /mnt



• After the mount is successful,  install grub with the command
  

  sudo grub-install –root-directory=/mnt “path”



• Unmount the drive with
  

  sudo unmount /mnt

Now, restart your system. Your grub will be restored with both Windows and Linux in the menu.