Whenever I boot my computer, I do not get any boot-menu to choose OS. It neither boots until I keep pressing ENTER (return). When it finally boots, it boots into UBUNTU and not windows. When earlier I used to get boot-menu, UBUNTU was the first option so presumably on pressing ENTER it is booting in UBUNTU.
Here is output from boot-repair. http://paste.ubuntu.com/p/kNw2DfHKMk/
The boot repair doesn't recognize Windows 10 installation in sda4: http://paste.ubuntu.com/p/FWSJ4zH7NT/
Press/hold Shift after the BIOS screen, you should see the GRUB boot menu.
If Windows is displayed on this screen you can select it from there.
You can also press the boot selection function key, usually F12 to get your UEFI bios to display the available boot options.
If everything works correctly with both of the above options you can use this How do I set the grub timeout and the grub default boot entry? to select a different timeout option on the GRUB screen so that it allows you enough time to make a selection without having to time either the F12 or Shift key presses at every future boot.
