I have recently installed Ubuntu 14.04 along side Windows 8 in my Samsung Series 5 np535u4c notebook in a 52 gb disk called Ubuntu.
Ubuntu grub screen showed up inttially (till I booted to Windows boot manager) but when I booted into Windows boot manager I can't see ubuntu grub menu anymore so I am uable to boot to Ubuntu. How can I boot into Ubuntu again?.
All I can see in boot options in bios is
I have had this before and I would need more information about your system (partitions, grub etc) to tell you the exact way. Your problem is mostly likely that you didn't install Windows and Ubuntu in the correct order or installed GRUB not properly. But one of these should solve your problem.
Go into your BIOS/UEFI and pick the disk where you have installed GRUB. Sometimes when an error occurs the BIOS/UEFI will switch disks in order to boot.
Use your USB Live Install to boot into your Ubuntu install. To do so pick your USB drive in your BIOS to boot from.
To make GRUB show up during startup, open /etc/default/grub with sudo. Comment out GRUB_HIDDEN_TIMEOUT=0 with a #.
Then type into the terminal sudo update-grub.
If none of the above worked, this should work most certainly. Here is how to install Boot-Repair
In order for Boot-Repair to work you need to create an unformatted partition with >2MB (it will tell you) and set the bios_grub boot flag. You can do this with GParted. Simply make free space for the partition by making one of the existing smaller and then add a new unformatted partition with the flag. Boot-Repair will take it from here.
