First I would suggest a "hard reset". Simply unplug the oven for a minute or two, then try again.
If it still fails, it may be that the keypad has failed, or there is a bad connection due to moisture, grease, etc.
This is an Australian model, so it's hard for me to give more specific information.
But one some US models the LCD and keypad connect to the circuit board via a rubber "zebra strip" and losing that connection can result in a loss of display segments and / or key response.
I've attached a diagram showing where one can clean to restore operation in this case.We're
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