Device Type missing from Device Manager

The Device Manager no longer shows "Imaging Devices" as one of the available
device types. It's very likely my fault, and I don't know how to fix it.

I was struggling to get a Canon flatbed scanner to work with my new desktop
system (a separate problem). Following directions from Canon technical
support, I opened device manager, found the scanner listed under "Imaging
Devices", right clicked, then clicked "Uninstall".

I seem to have uninstalled more than just the scanner, however - that's the
point at which "Imaging Devices" disappared.

Now, when I plug in the scanner (which still doesn't work), it comes up
under "unknown devices".

Also, Canon tech support had me search for usbscan.sys, which does not seem
to be anywhere on my hard drive (this was after the accident with the Device
Manager.)

so, how badly did I mess up?