Accessing printer on home network

I use a lap-top hard wired to a Netgear router in another room. Another PC stands next to the router, this PC is connected to a Canon iP4000 printer. I have always been able to print on this from my lap-top (using the other PC as a server ?) Recently when trying to print from the lap-top I get a message that the printer is off-line. When I disply the local network on the lap-top the Canon clearly shows there. I have dispensed with the old monitor on the desk-top and now can't access this PC to see what's amiss. Would appreciate any help.

Was just about to edit my post ! If I take the lap-top to the printer and connect via USB it works OK

I don't have another PC on the network. It consists of a lap-top, a desk-top, and a printer, with a Netgear router hard-wired to the lap-top and other PC, the latter is USB attached to the Canon printer.

PrinterPC has XP and PC has Win 7, what I don't understand is why the connection has ceased after always being OK ? In the meantime I'll try to borrow another PC. It's pretty easy really for me to take the lap-top to the other room if the worst came to the worst. The files on XP are accessible on the lap-top and the Canon pic shows when I click on "Network"

OK, have tried that. Think I might live with this situation for the moment.
Very many thanks for your help.