If Windows sees the Canon, but doesn't connect to it, you might try a different piece of scanning software. Another fix is to try doing it from an admin account. I have had a very old 8400F, which Windows says is incompatible with Win7 and up, but it scans perfectly in compatibility mode. I also have two different Canon MP printer/scanners, and I've used them and the 8400F on one laptop, first with Vista, then with Win7, and on a newer laptop, first with Win7, then with Win8, now with Win8.1.
I found this question because I was looking to see if there was a new solution to the eternal Canon issue with its software: right at this moment, Photoshop and Photoshop Elements both scan just fine on the Win8.1 machine, as does Windows Fax and Scan as well as Omnipage 18, Arcsoft PhotoStudio, and SilverFast--but Canon's own MP Navigator suddenly doesn't "see" the scanner, although it did a week or two ago. It takes a long time to connect to the scanner, then tells me that the scanner is disconnected, that there's an "error" with the scanner driver, which is obviously absurd since all the other programs see it just fine. Reinstalling didn't fix it. It'll probably work again in a week or two, thank you Canon. (The problem is that I want to use the scangear driver, because it is more versatile than the scanning options you can get otherwise. To "adjust the quality of the scanned picture" from the basic scanning dialog box does not give enough options.) If I were you, I'd go to the device manager, then imaging devices, and see if Windows thinks that they are all working properly. One trick that sometimes works is to disable the device, then re-enable it.
I've had a nightmare ever since getting my first Canon on 1/4/06 (the 8400F), and then the MP printer/scanners a few years ago. The physical aspect of their products is excellent: the problems are the drivers and the software. I've had to uninstall/reinstall both their drivers and the Canon programs literally dozens of times over the years. With the old Windows 7 laptop, I eventually had to do all my scanning from an admin account, thank you Canon. That did minimize the number of uninstall/reinstalls necessary.
I would uninstall all the Canon software and drivers, preferably using Revo to make sure all the miscellaneous files and folders are deleted; make sure that you reboot when you're through, then reinstall everything from an admin account, and reboot then also (this is for any Windows from Vista on.)
Before doing that, you ought to run sfc /scannow (you have to use an elevated command prompt), just for the heck of it, and there's no law against running scandisk regularly either, although, on a non-SSD machine, it takes an eternity. If nothing still works, I'd go to Microsoft's site and run any relevant automatic fixes. If that doesn't work, well, there do exist other scanner manufacturers.