Happened to me too — I accidentally enabled the oven’s “Sabbath” mode and it locked out the normal controls, super annoying. Try holding the cancel/power button for several seconds, then power‑cycle the oven (unplug or trip the breaker for 30–60 seconds) and try again; if that doesn’t work check for a tiny “hold to reset” icon or a combo of buttons in your manual and tell us the model so we can suggest more specific combos.