Yikes .. lost all nnml groups

[reader <hput3@fastmail.fm>]

Not sure how this happened but I have lost access to all but 2 nnml
groups.  Several dozens of nnml groups show up with an asterisk (*) in
front and are unusable.

I'm not sure if the following is related but did happen at about the
same time:

One of the servers I use (newsguy.com) since 1996, has gone belly up.
Its presence online has totally disappeared.  And I've received in
snail mail a notice about a bankruptcy proceeding concerning newsguy.

More actual facts regarding the situation:

I've checked the `active' file in ~/Mail and sure enough it shows only
the 2 groups that are still accessible.

I see all the dozens of directories containing my nnml files for the
groups are physically present under ~/Mail/

What can I do?

Note that since this is a zfs filesystem HOST, I do have copies going
back several months.

However, I'm not sure if I were to find the most recent ~/Mail/active
file where all nnml groups are listed (or at least most of them), how
I should proceed.

Will I need to substitute the more complete `active' file? Or will I
need to substitute all gnus' rc files of that same date for the
current ones?

If I do that I guess I can assume what ever has happened in news and
mail since the date of that more complete set of rc files will just be
gone.

Can anyone list which related files should be switched with the
current ones?

Is there some better way to proceed?