I accidentally restored BIOS on my dell Inspiron 5559 which was dual booting earlier with Windows 10 and Ubuntu-16.04. After restoring BIOS, GRUB got deleted which I repaired using boot-repair. I restarted the system and GRUB successfully loaded. I wanted to make sure that windows was okay, so I booted into Windows.
The problem arose when I restarted from Windows. GRUB was nowhere to be seen after restarting from Windows.
