For XP
Turn printer on
Start
Settings
Printers and faxes
Left click the printer icon
Click the word printer
Remove check from use printer offline, and make sure it is set as default printer and restart your computer
For Windows 7
Turn printer on
Start
Programs
Devices and Printers
Right click the printer icon
Click see what’s printing
Click the word printer
Remove check from use printer offline
Make sure it is your default printer and restart your computer
MAC
Turn printer on
1 - Open System Preferences by clicking on the icon in the Dock.
2 - Go to the Print & Fax control panel under the Hardware category.
3 - Select the printer you want to take online from the list on the left side of the screen. Then click on the "Open Print Queue" button.
4 - Click on the "Resume Printer" button at the top of the queue window to change the printer from offline to online. Now, restart your computer