Does your Gateway DX4200 computer have Windows XP, Vista, or 7 or 8, or 10?
You should see the function keys F1 to F12 at the top row of the keyboard.
Can you shut down the Gateway desktop computer
, then connect the Windows*****to the computer
, then turn on the computer
, then keep tapping key F10 to see if you get a boot menu
; (if needed, try the same steps again but with key F12 and/or key Esc.)
; then use the up/down button to select / highlight the USB device, then press Enter key and continue.
; if needed, use key F1 and/or F2 to go to BIOS/Setup menu, then set up the Boot / Startup order with the USB device as the first order, then save / exit, and continue.
When you are available, please reply at the box below to continue troubleshooting. Thank you.