Is this a new toner cartridge? It won't print if you do not pull the yellow shipping tape out of the cartridge. If you have printed successfully with this toner then it is possible that the laser beam path is blocked or out of alignment. The laser beam path is from the front top of the printer to the wide but thin window on the print cartridge. Print a test page and open the top about half way through printing, remove the toner cartridge and lift the flap that protects the imaging drum, look to see if there is an image. The next check is to pull the toner cartridge out and check the contacts or try a known good toner cartridge. If the problem is not caused by laser blockage or dirty contacts then the probability is a bad power supply is no longer supply the high voltages needed to develop and transfer the image.