I do understand similar questions already exist. Yet mine seems to be a problem that despite trying hard to address, I haven't been able to solve. Despite having a working Ubuntu LTs 14.04 installation on my dual-booted laptop, the GRUB loader menu does not appear. It boots straight into Windows 8.1. I've tried the existing solutions such as using Boot Repair, or running the bcdedit command in Windows and the like.
Mine is a HP Laptop with 64-bit processor.
I've made the following observations:
1. I don't have the 'Boot from EFI file' option listed in my BIOS boot order menu. It only has 'OS Boot Manager' that defaults to the Windows bootloader.
2. The Secure Boot is disabled.
3. I had formatted and re-installed my Ubuntu over an earlier installation (same version) owing to me screwing up the OS by installing too many packages. The installation completed successfully, yet I can't access the GRUB menu at the startup. The Linux can only be accessed by doing Shift+Restart from Windows side-bar and then choosing ubuntu as the boot device.
4. The paste bin URL generated by Boot-Repair is as follows:
The Paste-Bin Boot-Repair URL
It would be great if someone can help me out figuring how to get back to my feet with Ubuntu.