07-04-2014 11:08 AM
Welcome to the HP Support Forums!
I understand you are looking to get you Officejet 4500 out of an offline status. What is the Operating System installed on your computer, Windows or Mac? Also, what is the connection type between the printer and the computer?
If you open this link: Error messages displayed on computer, select your Operating System, then under Connection & communication errors click on "Printer is offline" you will be able to view and follow along the troubleshooting steps for such an issue.