I have had a fight with my computer for 2 days now.
After running boot-repair multiple times in different ways, it always comes down to this. http://paste.ubuntu.com/6382341/
Also this seems to be part of the problem. ''Locked-ESP detected. You may want to retry after creating a /boot/efi partition (FAT32, 100MB~250MB, start of the disk, boot flag). This can be performed via tools such as gParted. Then select this partition via the [Separate /boot/efi partition:] option of [Boot Repair].''
So I installed Ubuntu 12.04. alongside with pre-installed Windows 8 on Lenovo G500. I used it successfully for a few days for various programming tasks, installing software, plug ins, etc.. Everything worked perfectly. But after that I rebooted to Windows and used that for a day or two. Now a few days ago that I tried to return to Ubuntu, the Grub option doesn't show up at all and I'm directed directly to Windows8 from star up. I tried going to BIOS and Boot menu, but neither of those show Ubuntu. I started my computer now from a USB drive with Ubuntu, and that recognizes that I have Ubuntu installed on my computer already. So the Ubuntu still is there, it's been recognized, but I can't access it.
I have secure boot disabled and from the power options the other option unticked (quick start up or something).
I've gone through a lot of posts and googling for different solutions. But this time nothing seemed to work and I'm helpless.
As far as I have understood the problem of 'No boot loader is installed in the MBR of /dev/sda' is because it's somehow hidden by windows, so I need to make it visible for boot-repair? And this I don't know 'Syslinux MBR (4.04 and higher) is installed in the MBR of /dev/sdb'... I'm quite lost. Help appreciated here, thank you!