I was using windows 8.1 in dual boot with Ubuntu 16.04 for over 4 months or so. I usually booted to Ubuntu where I got those four options to start ubuntu, advanced boot options, start windows, etc. One fine day, my laptop booted to windows 8.1 by default. To look into the matter, I rebooted the laptop and paused the startup and pressed F9 key to view all boot device options.
According to the device priority order, ubuntu still was at the higher level of priority than windows, still, I chose to boot ubuntu. Next thing which I was seeing was my laptop booting to windows. No grub menu and nothing.
I saw various similar questions on StackExchange sites but none of the solutions seemed to be working for me. Any insight on how to go about resolving this?