I have a duracraft cool mist humdiifer and is starts but water inside doesn't go down even after few days

If there is water in it, it sounds like the ultrasonic unit failed.

it has a quiet operation when you got it brand new did it put out mist

with cool mist humidifiers your not suppose to see any mist. if it's a warm mist there should be. but by your model number i'm finding that it's a cool mist. that's why your not seeing any mist.

Fill it to with in an inch of full, add two tablespoons of clorox and fill it the rest of the way. Run it for a few minutes and then just let it sit over night. The next day empty it out and refill it with fresh water and one teaspoon of clorox. You will be good to go.

Located My Manual:
Hope this helps!

1. Remove tank from base. Turn upside down and unscrew filling cap. Fill tank with clean, cool, distilled, or tap water. Water temp should NEVER be too hot or too cold. Return tank to base and let sit for a few minutes. Be sure the filling cap of the tank is tightened firmly.

2. Plug power cord into a 110-120V AC wall outlet only. Turn power switch to "on" position. Power light will illuminate. Turn mist nozzle until desired level is being released. Aim nozzle away from furniture and walls.

3. Always turn humidifier off when water runs* out. Unit will continue to operate when tank is empty.
*Humidifier will run up to 12 hrs on low; 6 hrs on high.

DO NOT LET WATER SIT IN TANK FOR LONG. THIS CAN ENCOURAGE BACTERIAL GROWTH.
Place unit on level surface away from direct sunlight.
DO NOT ADD MEDICATION OF ANY TYPE INTO THE NOZZLE, BASE, OR WATER TANK.
ALWAYS LEAVE ROOM DOOR PARTLY OPEN. DO NOT MOVE, TILT, OR EMPTY WHILE OPERATING.

Mild bleach and water solution for cleaning, never detergent.
Clean every 3rd day during use. Clean after long storage
Humidity varies from room to room. Aim for 30 - 50% relative humidity. If windows/ walls fog or frost, reduce mist intensity. If room too humid, ventilate by opening door or window; adjust mist intensity.

Hi have a look at this:
http://www.appliancefactoryparts.com/content/pdfs/111854.pdf

if you can take it out side and plug it in, put some bleach in it and let it run for a few minutes. then wash it out and run the rest of it out.