Sideways Lighting Bolt icon please help Urgent

Ok so when I try to print from my HP Photosmart C8180 printer the printer options appear with a sieways lighting bolt that is yellow saying that the printer is offline. Does anyone know how to fix this? I have unplugged it, plugged it back in, checked the internet, which is working and nothing is working. I switched the printer to my laptop and it worked but it still wont work from my desktop. My Mac is a OS X 10.7.5.

Anyone know what to do?