how to make a usb drive bootable with ubuntu in windows

Without this enabled, the BIOS won't even see USB devices during the boot process, and it will just load the OS that it is programmed to load without looking at anything else. Most modern UEFI BIOSes, in order to speed up the boot process, don't usually load drivers to read USB devices and legacy boot sectors - and this has to be selected and enabled manually. You can also change the boot order here - but be sure to save your selection by pressing F10 or whatever the on-screen instructions say - otherwise any changes you made will just be ignored. Most modern BIOSes let you select a boot device from its main page, by simply pressing ENTER on the relevant device.

Option 1: Enter the BIOS and select the boot device from there. With the drive inserted, there are two fool-proof ways to select your boot device: in your case just a plain Windows install disk, on a medium that Windows has built in drivers for, and will be able to read once booted.)

Make sure your boot device is plugged in - and bootable - meaning it just needs the right files on it - either a UEFI Boot file, in a FAT file system, or formatted with a legacy boot sector with boot files compatible with that boot sector. Most modern computers with a UEFI BIOS will jump directly to the first installed boot loader, and not give you any time to choose an OS.

How to make a usb drive bootable with ubuntu in windows