If you need to create a bootable USB for Windows 7 or Windows 8.x, a good way to do so is with WiNToBootic. With this tool, you'll simply need an ISO or DVD image with which you can create a USB stick ready to install Windows on any other computer.
Create your USB memory with an installable Windows
You'll be able to create an installable version of the operating system in only a few steps thanks to the simple design of its interface and the fact that allows almost anyone to use it. We simply have to open the files that we want to copy to the USB unit and let the program to do the rest of the dirty work, only taking a few minutes to complete the operation. Previously, we'll have to format the USB drive to make sure it's completely clean and doesn't contain any other kind of file.
Thanks to this software to create bootable discs, we can have our own USB drive ready to recover any computer that needs an operating system installation from scratch.