Losing GRUB2 happen again this time, this happens because I have updated the originally installed Windows 7 on my netbook. Like it or not, I can't use Ubuntu 11.04 Natty Narwhal or BackTrack 5 Revolution, the Operating System only can access directly into Windows 7. For this time, I posted how to restoring GRUB2 on Ubuntu 11.04. A simple step that is as follows :
1. Boot to Netbook with LiveUSB Ubuntu 11.04
2. Select "Try Ubuntu without Installing"
3. if already in ubuntu desktop, open terminal with keyboard key combination CTRL + ALT + T
4. Type sudo fdisk -l
This command serves to find the location of your linux root. In my case, I found in sda9
5. Then type sudo mount /dev/sda9 /mnt
6. Then type sudo grub-install --root-directory=/mnt/ /dev/sda
7. And then, update GRUB with the command sudo update-grub
8. The last, reboot Netbook with the command sudo reboot from your terminal.
Don't forget to change the setting boot loader from USB to hard drive in the BIOS.
Then when the BIOS setting is completed, then GRUB2 back again :)