Can't install Ubuntu 12.10 from USB stick on laptop with Windows
If USB doesn't show in boot menu, probably there's something wrong with it. Perhaps you should format it and see if it shows in the boot menu without anything else in it. You should proceed with creating Ubuntu live USB only after you can see the reformatted empty USB. If it doesn't show up perhaps you should try another one.
Maybe you should try doing it with a DVD. I had that issue when trying to boot Lubuntu from my perfectly fine USB drive, then tried the DVD player, and it worked perfectly