look in your manual for print head cleaning and other maintenance stuff.
usually you will tke out the print head (after taking cartridges out) and put the tip of it in some shallow window cleaner stuff and leave it sitting there for 30 mins. then wipe the windows cleaner off and leave it sitting for an hour or so. then reinsert it back into the printer and do the maintenance stuff again (in printing preferences or something) . then it should work. if this is not the case, contact Dell and they will help you.
if you cannot get to the printer maintenance, you have to make sure that your printer's software is installed correctly (maybe not only the drivers, but also special software you will have gotten with a CD)
in any case, i hope the problem is resolved shortly, and without too much trouble