DISHWASHER HELP there is no water?

Ok my uncle put in a new sink, when we ran the dishwasher though lots of water spouted through the air vent. Then it cleaned dishes for like two cycles and now it's dead. It refuses to fill up. He claimed nothing is wrong so we won't get a repairman in. Can anyone help me DIY fix this? Could he have detached something? PLEASE BE VERY DETAILED thank you so much