Booting impossible cause GRUB rescue won't let me

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http://askubuntu.com – I created two bootable USB: Lubuntu 12.10 and Ubuntu 12.04 from my windows machine. SCENE 1 I installed Ubuntu 12.04, everything is fine. A popup window appears that says something like "I have successfully installed the operating system and a reboot is required." I am about to click the reboot now button, when the electricity went off (No laptop battery, dammit)! Now I boot back, and found out that my Ubuntu will only normally boot if the USB is plugged in, if I removed it, only the blinking insert cursor will just be there for me. SCENE 2 With my crazy mind, I thought of installing the (HowTos)