Is this a "CANON Pixma iP2600 Photo Printer"? Are you running a 64-bit Ubuntu install? There's a full write-up over here
on how to fix your problem.
Otherwise, you'll want to hit the following sites;
One of their threads specific to your printer.
Ubuntu Forum post with Drivers
And if this is connected via USB, maybe check the output of "lsusb" to see if the printer's showing up?
(Note: If you post any sort of output here, be sure to wrap it in [code]
Else your post may be too long, or to garbled to read, and most readers will ignore it.)