how to fix my diplomat model no.HJA8630?

I recently moved house and there is a Diplomat integrated dishwasher model no.HJA8630 fitted.For three weeks the item was in working order.Last week however when my wife went to start it,it would not begin its cycle.We read the instructions and removed filters and added salt etc.but this has made no difference.The lights are all on but when the door is closed there is nothing.Can you help