Hi Paul! Take off the cover and see if the light is green and the switch is on. Sometimes if there is a surge in power, it will reset the ice machine; check the paddle to see if it moves. If yes, just turn the switch off for about 30 seconds and then on again. Afterward, wait a few minutes for the carriage to turn and water start to flow. Watch your fingers! If no water, you will need to replace it.
If this is a commercial unit, just take off the front panel and see if it cycles (20 minutes). If it does, but no ice is made, try cleaning the compressor or pour some hot water over the inline, to defrost it. ( Old Restaurant Trick).
Good luck! James.