I had a problem of a similar nature, maybe not affecting perl itself, but making enough of a mess in my module library that perl was seriously disabled.
TimeMachine to the rescue. I had learned (the hard way, after a real disk crash) that this now-standard utility is a Really Good Thing -- it works. So my external/removable TimeMachine drive had the pre-corruption version of the module library directory tree, and things were back to normal with hardly any fuss.
You have been using TimeMachine, haven't you? Deleting your current foobar perl and restoring a pre-foobar version from backup is quick work (and especially effective, if you don't know what went wrong, but you do know roughly when it went wrong). The tool lets you browse older versions of relevant paths before restoring, to get a better idea of what you did and what you need to do to fix it.
