I was using the kitchen sink at my aunts- when I went to use the sprayer hose, the water stopped. What I didn't know was that the sprayer doesn't work. What can be done to fix this without having to call a plumber?

You have a problem with the diverter. The diverter is located at the base of the spout in the front section. Try this. Remove the handle and any plate that might cover the spout. Remove the retaining nut and pull the spout up. Check and clean out around the diverter. Now place a pan over the valve and turn the water on for a few seconds to flush out the diverter opening. Reassemble and test, Sprayer work now? Let me know, Tom