Knoppix isn't always the best tool for NTFS recovery, I'm afraid (take a look at some of the posts here about Hiren's BootCD, for instance.) One thing to check is whether you have a BIOS switch for "native-mode" SATA drives. I've experienced that having to be set one way for Windows and another for Knoppix, assuming you have a SATA drive. We'll be able to help much more if you give us more details - brand and model, and output of the "lspci -v" command (start a command prompt window with the black computer-monitor-looking icon on the lower left and type that in with a <return> after, then copy the output to the posting window.)

Cheers!
Krishna