Ink cartridge can't be recognized

Question

All of a sudden my printer is telling me that the ink cartridges that have been in there all year are now "cannot be recognized" I have checked and they are the right kind of ink cartridges. I have taken them out and put them back in and they seem to be installed correctly, but my printer still "cannont recognize the following ink cartridges" and won't print. any suggestions? Thank you!