This can be especially helpful if you're pretty certain that your Mac's the problem, not the printer (if your other computers can print just fine). You'll want to use this only as a last resort, though, because you'll have to set up all of your printers and scanners again.
Here's how you do it:
• Open System Preferences from the Apple menu and click "Printers & Scanners"
• Right or Control click on the white box on the left of the tab (where your devices are listed)
• Choose "Reset printing system..." and click OK
• Wait for your Mac to complete the task (which can take a little while) and after it's finished, select the plus (+) button on the "Printers & Scanners" window to walk through adding your devices back in