Scanner doesn't work - Canon PIXMA MP240 All-In-One InkJet Printer

You most probably need to install/re-install the printer/scanner software and scanner manager.
http://www.usa.canon.com/cusa/support/consumer/printers_multifunction/pixma_mp_series/pixma_mp240#DriversAndSoftware
Above please find your canon drivers, download these and install as Administrator...also make sure you install the scanner driver as well as the printer driver...also you need a Scan manager too..
If you have installed the scanner before you need to remove it from device manager, by removing the drivers. Once that's done, unplug the printer. Then reboot,.(If you have a CD/DVD that came with the unit, you can and should use this, else download the files from the link given) Then install the new software now do NOT connect the device, only connect when/if asked, or at the end of the install and after a reboot, then, plug in the printer/scanner.
It should be detected and install itself, it may ask for drivers if so, show it where they are, and it should proceed and you should now be able to scan and print, now you must use a scanning program, and or the interface that came with the unit, Canon Scanmanager, however, if installed correctly you can also scan into Mspaint, Word, Publisher etc. but there are many free scan manager programs on the 'net. a good one is Vuescan, http://www.hamrick.com/ now the beauty of this program is that is doesn't require any "Drivers" as it has it's own, so as long as the scanner physically works, then this program will scan with it.
Another is Freekapture ,http://www.freewarefiles.com/FreeKapture_program_32165.html
This uses TWAIN drivers, that should install at the same time.
http://www.ehow.com/how_2006169_troubleshoot-scanner-printer.html
http://www.tutorialsweb.com/computers/printers-scanners/Tools-to-troubleshooting-printer-scanner-problems.htm
Above are a couple of DIY sites to help also.

Not alot to go on here.
Try reinstall the software.
Does it copy when you use the copy button on the printer?