Epson r320 printer will not read any memory cards

Does the green light come on when you insert a card? Most likely that if it can not read the cards, and it is just not your PC failing to communicate with the card reader, then the mainboard is probably faulty. If it's in warranty get Epson to replace it. If not, you could see if you can source another R320 from eBay, (or similar) that has a different problem and swap the mainboards. You would also need the service utility to do this as you MUST change the print head ID on the new mainboard. Another alternative is to simply buy a cheap card reader and plug it into the USB input port on the printer. If the mainboard is faulty, this may not work though. Still you could then just plug the reader into your PC instead.