1) check the USB cable is connected properly behind the monitor and CPU.
2) If it's connected then take the cable out from CPU and plug back in.
3) Go to configuration screen (for elo computer or elo touch screen go to elo configuration and for other go to egalaxy touch) and make sure you see your monitor there. if you don't see any monitor then your usb cable is not working or cable is not connected correctly.
There is no configuration for touch screen in Cronypos.