HP Laserjet 2550n Printing Problems

When I send a document to print the printer warms up but then stops and the error, ready and another light, light up (no blinking-solid lights). I’ve changed the drum since it was low, I’ve put in different quality paper, unplugged it a million times and I called HP support and they lady told me to use a USB cord so I did it and I went to choose the port for USB and it wasn’t there. Has anyone else had this type of problem? HELP PLEASE.