You might want your computer to clean the printer heads, (or you could do that yourself)
I think you go Start> Control Panel (or printers, if you dont see Printers, then you will find it in control panel) and then you find the printer thats not working. Right click and select Clean Heads if its there, or click properties if its not. In Properties window, see if you can find clean heads anywhere.
Also; make sure that the printer model and whatnot is correct.