I have Windows 10 and Kubuntu 14.04 in Dual Boot.
While on Windows, I choose "Update and Restart". I left and when I came back, the computer was on Kubuntu Login Screen (Probably GRUB automatic launch). I didn't log, but choose restart in order to check the Windows update.
Now instead of GRUB, I have a HP screen saying "Boot Device not Found".
With LiveCD, I can access my files.
What should I do in order to retrieve the GRUB without reinstalling any OS ?