HOW TO BOOT FROM YOUR RESTORE USB DEVICE
To make the PC boot from the USB restore device you need to insert it in the USB port then boot the system. At this point you may see something like "press F2 to enter setup" it may also be Del or Return. Normally it is the F2 key. You may have to use another device to google what the key is for your particular computer.
You now have the setup menu on and at the bottom there will be Enter Setup. Use the arrow keys to select that and press return.
Next slide over to "boot". Use the arrow keys to select "Removable Device" then use the "+" key to move it to the top of the list.
At this point you want to use whatever it says at the bottom to save settings (normally it's F9). Then select "yes" and press return. Then the system will continue to boot from the USB device. Remember is you have an external drive hooked up to unplug it. As well after installing windows again you will want to follow the steps again to set "Hard Drive" to the top slot to boot from it or it will try to boot from your external drive.