Hi. Check your usb device is shown in the bios before you try to boot from it. My dvd drive and one of my usb memory sticks were not shown in the bios so the bios will not recognise them to boot from. If you have one that is shown in the bios(usb memory stick). I used a program called wintoflash which can be found if you google it, all you do is put in your original operating system into a dvd drive on a other computer, make sure you have a usb stick installed and follow the instructions of wintoflash. It takes a while to install but it works. hope this helps you.