The nozzles on the ink cartridge itself can sometimes clog or plug if the printer has not been used for a long time. Take the cartridge out and place it in a shallow saucer of warm water. In a minute or two the ink should start to color the water. Take the cartridge out and dry it, then replace it in the printer and run the print head cleaning program.
If your printer seems to be printing weird text and strange characters, it may be a driver problem inside your computer, not with your printer. Go to the manufacturer's site and download the most recent drivers for your printer, install them and then try to print again.