I think I may have messed up my knoppix USB, because I get a boot error when I try and boot from it. I have another USB I can use. But I cannot access the files that were on the one that does not boot even
if I put in the 'bad' USB when booting with the good one.

Can I safely 'Install knoppix to disk' from that does work to the one that doesn't without losing the data and files I had?