With reference to this http://ubuntuforums.org/showthread.php?t=2144073 , I downloaded Testdisk 6.13 on ubuntu 12.04.2 liveusb to fix the hard disk. After extracting, I double clicked the testdisk_static and 2 other executables, nothing showed nor worked, I clicked them again a few times, still nothing happened. However, I found the whole ubuntu environment was becoming lagging after clicking the testdisk_static and 2 other executables though nothing appeared. I then clicked restart.

My laptop didn't show the BIOS screen anymore, just blank and beep then turned off by itself. I unplugged the battery, power cable, pressed down the power button and tried to on, the BIOS screen still didn't show, just blank screen, after 4 seconds after the CD Drive light was gone and beep sound, the laptop turned off by itself. I doubt if the TestDisk_Static and 2 other executables could damage the BIOS ? Motherboard ? Chip ? I clicked them many times but nothing prompted, just noticed the system was getting lagging & slower. After restart, my laptop didn't boot with BIOS screen anymore, just blank screen and turned off after a beep & after the CD Drive light. Now I deeply regret that I shouldn't install ubuntu in a rush screwing up everything, earlier WINXP and now the whole laptop is sacrificed