If you have no water, the first thing to do is to check that your water meter has not been turned off.
Next, check whether other people in the street are affected to eliminate whether your local water authority is working in your area. If it just your property that is affected, turn on a number of taps and see if your water meter ticks over.
If the meter is ticking over, but there is no flow, then it is likely there is a blockage on the property side of the meter. If this is the case, then you should contact your who will assist with tree removal, storm damage etc.
If you have a serious emergency you should dial "000" for assistance from your local police, fire and/or ambulance service.