What brand of VFD is it? All the ones I've seen let you change the settings, but it's not always easy to figure out. Have you got the manual for that VFD?
Does your controller have a USB input? Have you tried all the USB outputs on your computer? Sometimes one doesn't respond, for reasons of its own. Have you tried twisting the Estop button to release it? Can you get tech support from whomever it was that built this machine?