That depends. If you normally run CPAN as root, then it stores its config
info (mirror locations, etc) in the global CPAN/Config.pm module, and the
only thing in .cpan will be downloaded tarballs, build trees, and so forth;
in other words, nothing critical.
If you don't run CPAN as root, then the config params are stored in .cpan/
CPAN/MyConfig.pm instead. This could be the case if you use CPAN to install
modules in your home directory, or if you're using a newer CPAN.pm that lets
you limit root authority to just the final "sudo make install".
If you want to "reset" CPAN, and if it's using a global CPAN::Config.pm,
then it might not be a bad idea to delete that too. CPAN::MyConfig.pm, of
course, lives under .cpan, so deleting the directory will catch it too.
After that, CPAN should prompt you to go through the initial configuration
steps again, setting up the default Makefile.PL arguments, choosing mirrors,
etc. And because you've deleted the cached info, it will fetch fresh copies
of its module and author indexes.
sherm--