my laptop fell out of the briefcase and now my keys z,x,c, v are not working. I took the keys off and put back on and sprayed air on them and still no luck
Sorrybut you make have actually broken the keyboard. Replacing a keyboard is fairly easy. I suggest you check with a vendor like txcesssurplus.com to see if they have a keyboard available for your particular model.
Also, if you have the proper warranty (depends on what you bought), Dell will replace for you.