Can't see USB hard drive to copy crashed HD files to

I am a new user to this game. I am trying to recover some data from a badly crashed laptop. Couldn't get it to load with anything else and have been staggered with the power of Knoppix which I can get to load and have seen some of the data files on the hard drive. I cannot seem to get it to read a USB external drive though nor work out how to copy the data across. Can somebody help please?

I have seen reports of some USB devices not mounting properly at times, don't know that I've seen any good feedback about how it was resolved. In general you would be advised to see the recovery faq (answer 5) and information about mounting drives in answer #6. Also be sure that the usb drive is attached when Knoppix is booted, that may help.