You cannot simply download and copy DLL files and have the scanner software or driver function.
The DLL files need to be 'registered' on the PC.
Is the scanner supported for the version of Windows you are using?
If not, you can copy all the DLLs you can find, and the scanner will still not work.
You need to get the correct version of the driver for your scanner and version of Windows from Visioneer.
Install the driver, and the scanner should work.
If the problem is with a softwareprogram that came with the scanner, you may need to purchase a newer version of the software from the company that provided the software.
Chas