System directly booting to Windows without showing GRUB menu [duplicate]

Solution 1:

If I understand you correctly, but it sounds like F9 would be the right choice. I'm not sure though because every PC I've ever owned uses F12 to select a boot device. If F9 doesn't work try F12. Basically you want to get to the menu where you'd select a boot device (like when you're booting from a live usb) and choose the correct partition.

All you have to do is arrow down to the partition ((device) with Ubuntu installed and press enter. Then open a terminal and type sudo update-grub. It should find Ubuntu and re-add it to the grub menu.

Solution 2:

In my case, I had to press and hold the Shift button during the boot of the system. This should allow the grub menu to show up. Then you only need access Ubuntu and set the grub options via "boot repair" or similar programs. I hope this helps!