Yikes..
 

Just goofed and exported a path in all lower case, and naturally I can't even "ls" or anything else like it. Where are paths stored, so I can change it back? Or is there and easier way to restore them?

I typed: export PATH=/usr/local/JKD1.5.0/bin:$path

No caps at the end.

Just relogin, problem fixed.

For the long way: export should be a shell built in, so no matter what PATH you have, it will always be found. Common places for the path are /bin and /usr/bin, and that should get the system usable. The distribution you use will probably store certain programs elsewhere, possibly there might be a /usr/games/bin, and thats not even looking at the /opt options. Typing "source ~/.bash_profile" should fix the issue. 'Source' is also a builtin i think.