How can I use these both OS on my laptop, without having to reinstall one? For my personal use I always had Ubuntu installed (13.10 32bit) as my single OS. Then for my new job I needed to install Win8.1 (64bit). Now I have these both OS on a separate partition, but I can boot only to a Win8.1 OS.
Is there a way that I can restore the Grub or whatever to do, in order to have a choice to boot any of my two OS (preferably without having to reinstall one)?