In adition, if not only your mirror list is screwed, you can do o conf init to have all the original questions asked of you.

If that doesn't work, try deleting ~/.cpan/CPAN/MyConfig.pm, or in extreme cases, the system-wide CPAN config file, which on Debian is located at /etc/perl/CPAN/Config.pm. YMMV.

You can still download and install packages (including CPAN.pm itself) manually, e.g. by browsing http://search.cpan.org/, finding the module you want, and clicking Download. Then follow the standard untar-make-make test-make install procedure.