If you have a printer that worked fine under OS X Mavericks, but stopped working when you upgraded to Yosemite, this thread may contain the answer:

Ricoh MP C2500 not printing after upgrading to Yosemite

Note that the fix included applies to several brands and models of printers, not just the Ricoh model mentioned in the thread title. The notes state, “This script should work on those that use the pxlmono/pxlcolor, hpijs, and samsung-gdi driver packages. It will not work for the m2300w driver at this point. I hope to be able to figure that one out too, but don’t count on it.”