Hi bnsrini.
I will be able to assist you.
If you are using the Windows operating system, the Canon MF Toolbox 4.9 scanning software can be downloaded at the website at the link below. Please select the file named [[Windows 32bit & 64bit] Tool Box Ver.4.9.1.1.mf18], listed under "Recommended Downloads".
imageCLASS D420 - Drivers & Downloads
If you are using the Mac OS operating system, the MF Toolbox is included in the scanner driver download. To access the program, please open [Applications] > [Canon MF Utilities].
Should you need further assistance with this issue, please call us at 1-800-OK-CANON (1-800-652-2666).