If the status of your printer or All-In-One is Offline or Paused you will be unable to print. Provided that the printer is connected and configured correctly, manually changing the printer's status will enable you to print again.
Your printer may become Paused following an error with a print job. Offline status may occur with network-capable printers like the Stylus SX515W where, after first setting up the printer on a USB connection, you then disconnect the USB cable and set it up as a network printer instead.
Checking the status of your printer in Windows 7:
Click on Start, then Devices and Printers.
Hover the mouse over the icon that represents your product. A pop-up window will display its status.
Alternatively, the status can be viewed by double clicking the printer icon. The window will be shown as below.
Changing the status of the printer:
Within the printers dialogue box click See what's printing.
Select the Printer tab, then untick Use Printer Offline from the menu.
If the printer is paused, untick Pause Printing from the menu.