The local water co. Informed us that we were using an astronomical amt of water for the amt of occupants within the home. A friend of mine suggested turning off all the water valves to check if the meter was still turning, & if it was, that we had a leak somewhere. So I turned off the valves under the washtub outside, under the kitchen sink,behind the toilets and under the sinks in three bathrooms, and the valve that supplied the water for our washer & refrigerator. After checking the meter I was to turn the valves back on. Two of the valves started leaking & had to be shut off again. The valve under the outside washtub leaking about a drop every two or three seconds, and the valve under the sink in the main bathroom was spraying water seriously. The leaks were fixed the next day & the water pressure in the bathroom has been so low since then in the sink as well as the shower.How can this be fixed?

Remove the showerhead, and the aerator from the end of the sink faucet spout and clean the debris from them.

You may consider replacing any valves that leak after you turn them off and back on again.

Any time you turn the main off and back on you have a chance of clogging something. Best advise to start out with is above. Take off shower heads and aerators and flush them.