I've installed Ubuntu 14.04.3 LTS from a USB drive, on a PC running Windows 8.1. But when I turn on my PC, I'm not presented with an option to choose to boot either Windows or Ubuntu. Instead, I'm taken straight to Windows. I've reinstalled Ubuntu (from the same USB drive), and nothing's changed. Moreover, Ubuntu doesn't appear in my list of programs in the Windows control panel. How can I boot into Ubuntu?
Someone suggested I boot the USB drive and type the commands: sudo fdisk -l sudo grub-install /dev/
Here's the output of these commands: Output of sudo commands