all my groups inactive

[John Hunter]

I have a variety (many hundreds) of mail and news groups.  I think I
hit some keystroke by accident that made all of them inactive, causing
my group buffer to look like
http://nitace.bsd.uchicago.edu:8080/files/share/Screenshot-Emacs.png.

Even if I try and enter one with (gnus-topic-select-group t) I get the
error, for example, 

  No such group: admin

However, if I get a new message to that group, or copy an existing
message into that group, eg, with gnus-summary-copy-article, I get the
no such group prompt asking me if I want to create it.  If I say yes,
the article is put in the group, the file number for nnml is correct,
and I can subsequently enter the group.

How can I undo this travesty?

Thanks,
JDH