I'm running a dual-boot system with Windows 8.1 and Ubuntu 14.04. After reinstalling both OSs several times my System boots right into Windows.
Some information I gathered:
If I have a bootable USB (either Ubuntu or Windows) plug in and boot to the Windows recovery screen and select the boot from external device I can select Ubuntu and boot into it. There I installed the boot-repair tool which told me to deactivate the secure boot option in my BIOS, which I did, but which also didn't change anything. I ran boot-repair again and it got caught in an infinite loop doing the same things again and again with no option to cancel it. But I got the information log (http://paste.ubuntu.com/8121921/).
My guess is that either Windows overwrote the grub or that I installed it to the wrong partition. But I screwed my System several times by now and it's still not working as it did with the OEM which is kind of a big deal 'cause I kinda need some features back for school...but that's some other story...
So if someone could give me some (detailed) instructions on how to get grub to working again without killing Windows please tell me.