To make a long story (see below) short, where can I obtain the WIA driver that Windows 10 claims I need for my CanoScan 8400F scanner? Canon says the driver is included in Windows 10.
The long story:
In 2004 I purchased a new Canon CanoScan 8400F scanner.
In 2011 I purchased a new ASUS laptop (Intel Core i5-2410M CPU 230GHz 8GB x64-based processor) with Windows 7 pre-installed.
Using Canon's CanoScan Toolbox 4.9, the laptop and scanner communicated via USB to successfully scan photos and documents.
I never upgraded to Windows 8 or 8.1 and have no experience with those operating systems.
A few days ago I updated to Windows 10. The installation process did not remove CanoScan Toolbox 4.9.
When I tried to use CanoScan Toolbox 4.9 to scan something, ScanGear CS displayed: 'Cannot communicate with scanner.'
When I clicked 'OK' to dismiss that message, CanoScan Toolbox displayed: 'Unable to open TWAIN source.'
Shutting down the laptop and restarting it did not help.
Powering down the scanner and restoring the power did not help.
For CanoScan 8400F, www.usa.canon.com displays
'There is no driver for the OS Version you selected [Windows 10 (x64)]. The driver may be included in your OS or you may not need a driver.'
'Removing' CanoScan 8400F from Windows 10 and re-adding it did not help.
Eventually I discovered, installed, and tried the Windows Scan app.
Windows Scan displayed 'CanoScan' under 'Scanner'.
When I clicked 'CanoScan', Windows Scan displayed 'Problem connecting to scanner. We can't find a scanner. Attach it to your PC or go to PC settings to add it.'
In the 'Start' menu, I clicked on 'Settings'.
On the 'Settings' page, I clicked on 'Devices'.
The 'DEVICES' page listed 'CanoScan' among the 'Printers'. Why did Windows Scan tell me to add it?
I closed the 'DEVICES' page, pressed Windows+x, and pressed 'P' to display the classic Control Panel.
I selected 'Devices and Printers' and pressed Enter.
The first item under 'Devices' was 'CanoScan'.
I right clicked on 'CanoScan', clicked on 'Scan Properties', and clicked on 'Test Scanner or Camera'.
The sounds from CanoScan indicated that it was moving its scanning head.
Windows 10 displayed 'Test Successful Your imaging device successfully completed the diagnostic test.'
Backing out to 'Devices and Printers', I again right-clicked on 'CanoScan' under 'Devices' and clicked on 'Start Scan'.
Windows 10 displayed a dialog box containing an OK button and the text

1. Canon Wia Driver Install
2. Need Wia Driver For Scanner

'You need a WIA driver to use this device. Please install it from the installation CD or manufacturer's website and try again.'
I installed the WIA driver from the Canon CD, but that did not help.
Windows 10 gave no indication as to whether the installation succeeded or failed.
The Canon CD did not indicate whether the WIA driver was x32 or x64.
Did I remove the WIA driver included in Windows 10 when I 'removed' CanoScan from Windows 10? If so, how can I obtain the WIA driver again?
Thank you.

Canon Wia Driver Install

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Need Wia Driver For Scanner

1. WIA is a driver model implemented in Windows XP or later. It allows you to scan items without using an application. The procedure varies depending on the application. The following procedures are examples only. Refer to the application's manual for details. In Windows XP, you cannot scan using the WIA driver via a network connection.
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