I go to 'My Profile' several times per day and look through all threads where there have been posts in the past couple of days. (I don't usually go beyond that, as there's normally little point). So I can sometimes miss posts where there has been several days gap between posts.
After spending ages trying to get hold of the MP220 manual from the Canon website (which meant installing a new program on my own computer, rather than just downloading a pdf file - grrr!) I couldn't find any reference to setting up its wireless connectivity. So I checked out that printer's specification to see if it is actually wireless-enabled. It seems that IT ISN'T!!! So, since it can't 'talk' to your router, you CAN'T send it a signal from your laptop without using a USB cable. You need a wireless printer to do that!
You could theoretically create a network between your laptop and your desktop (so that your laptop gets your desktop to send the print instructions on to your printer) but that's an imperfect solution as you'd only be able to print from your laptop when the desktop was switched on.
I'm completely mystified as to how you got it to work in the past! Sorry!
Perhaps Canon's techies can help you (020 7660 0186, 0900-1700 M-F) but I can't actually see how! (There's also an email form here:
http://www.canon.co.uk/Support/Consumer_Products/Contact_Support/Index.aspx )