You need to be able to shine light through film to scan it. If you have a scanner that only reflects light off the film (i.e. a normal flatbed scanner without a transparency adapter), then you can’t scan film with it.
If your flatbed scanner has a lamp in the scanner lid, make sure you’ve plugged the cable from the scanner lid into the back of the scanner.
If you’re using a Canon scanner on 64-bit Windows, make sure you’re using the x64 version of VueScan 9.
Check to see that the “Input | Mode” option has a transparency option.
If you don’t have a film scanner, you might look into getting a used film scanner on eBay, in particular a used Epson flatbed scanner on eBay or a used Nikon film scanner on eBay.
You can always sell it again on eBay when you’re done with it. You might even sell the Nikon scanner for more than you paid for it - prices have been going up since Nikon stopped manufacturing film scanners.