Usually powering up the printer enables online mode.
I've only seen offline mode when i forget to turn the printer on.
Your printer is connected to the pc with a data cable(usb for example) right?
Won't connect otherwise.
I am unable to change my printer status from offline to online. What does this mean?
It means your PC is being perverse and is refusing to print for no apparent reason. Forget all this advice about what buttons to press to make it work. The only solution I find that works is to turn everything off, disconnect from mains, count to 10 then replug in and start again. Works every time.