XPS 14z 4 ke s on ke board have stopped working

When you press on one of the keys, do they go down as far as the others? If not, get a can of compressed air (you can get it at a local office supply shop, electronic store, Walmart, Meijers, K-Mart etc) and then turn off your laptop.  Now open the laptop so the lid is 90 to the bottom and set the laptop on a flat surface on one edge. Hold on to it while blowing the canned air under the keys. You will need to have the straw stuck in the nozzle so you can get under the keys. Once you have blown all the dust, hair, cookie crumbs and the like out from under the keys, set the laptop back down. Now look between the keys. Do you see any more hair? Use a toothpick to pull it above the keys, then grab it with your fingers or a set of tweezers. Once you have cleaned and leaned some more, turn the laptop back on and see if the keys work now.

If that does not work, you may need to purchase a new keyboard and replace it. They are fairly easy to replace.