If you are getting no valid accounts pop up when you are trying to print, follow the below instructions.

Open up the start menu and scroll down to "IT Support".

Once Opened, click on "Restart Printer Client". 

Once clicked on, a black box will appear and disappear quite quickly on your screen.

When the box has disappeared, try and print something again. If you still have no available accounts when printing then do get in contact with IT.