Epson ink cartridges have a memory chip that tells the printer how much ink is left in the cartridge. When the chip tells the printer that the cartridge is empty, the printer software alerts the user and refuses to print. Unfortunately, a chip can tell the printer the ink is gone when it really isn't. You can reset the chip in a printer cartridge by using a paper clip.
Grasp one of the ends of a metal paper clip and bend it outward. The end should be at a 90-degree angle from the rest of the paper clip.
Remove the ink cartridge from the printer. Look on the bottom of the cartridge. You should see a chip with a small hole underneath.
Insert the end of the paper clip into the hole and press down. Remove the paper clip.
Insert the printer cartridge back into the print head and continue printing as normal.