Network printer is connected but will not ping/print

[pip9017]

Hi,
I work at a print shop - yesterday, I was just doing my thing and then our printers stopped working for no reason at all! The MAC still works strange enough. We changed the router, the hub, and disabled any firewalls but it still doesn't see the printers. The connection has not changed and has been the same for 3 years. Any suggestions??? -MT

 

[tkrl26]

What kind of printers are they?

 

[pip9017]

The prints are: Xerox 700, Canon Imagerunner 8500, and Canon 600. They were all working fine and have been for years and then like, the connection was just suddenly lost. It keeps saying that it's "ready" under the Printer/Fax screen (work mostly on the PC) and not offline.