First off, turn off the printer in front and then in back, then unplug the printer for at least 5 minutes. Plug it back in and turn it on in back, then in front. If that doesn't fix it try updating the firmware. You can get the latest version from Rolanddga.com in the support section. Just follow the trail to your printer model and look for firmware. You can find the instructions there as well.
good luck