Can a blunt knife be sharpened?
You will not be able to sharpen it with a steel as per Ching Chong's answer. You will be able to sharpen it with a couple of sharpening stones. If the blade is totally blunt you will need a reasonably coarse one to bring the edge back, and a finer one to refine the edge. Then you can strop it on the steel or the back of a leather belt to remove the burr. 

However, unless you have experience in sharpening, the results will probably not be worth the outlay for the stones. That is, unless you use these knives for practice, then invest in a decent one afterwards. There are any number of videos on YouTube showing you how to sharpen kitchen (or any other kind of) knives.