I just installed 12.04 LTS onto my Acer Aspire One from a USB thumbdrive, and I cannot reboot unless I boot from the USB drive. If I have the USB drive plugged in, it boots, and it looks like the system is running of the HDD (/ is mounted from there, the USB drive is /media/PENDRIVE, everything works fine when I unmount it, etc).
If I reboot with no USB drive mounted, I just get a flashing cursor. It looks like a misconfigured boot loader. The Terminal tells me that grub is not installed ... so just how does Ubuntu boot these days, and how can I make the HDD bootable?
Possibly you have installed grub in the usb not in hard disk.
To install grub in hard disk,
install boot-repair by using the following commands.
sudo add-apt-repository ppa:yannubuntu/boot-repair && sudo apt-get update
sudo apt-get install -y boot-repair && boot-repair
paste.ubuntu.com/
) and post the url.A detail reading of boot-repair may help you, https://help.ubuntu.com/community/Boot-Repair