Network hardware disappeared after re-boot

[Charlie Gibbs <cgibbs@surfnaked.ca>]

I have a Lenovo T410 laptop running Bookworm (12.11 according to
/etc/debian_version).  It's been running perfectly for months without
a re-boot - but after a re-boot today (more on this later) it can no
longer find network hardware, either wi-fi or Ethernet.  "ip addr" and
/etc/network/interfaces only contain entries for the loopback device
(lo); /etc/network/interfaces.d is empty.  Aside from the loss of
networking, the machine seems to be running normally (although
VirtualBox can no longer bring up a Windows XP virtual machine
which uses the networking hardware).

This machine also contains Windows 7 in a dual boot (although
I seldom use it).  When I bring it up it can find and use the
networking hardware.

Prior to the reboot before the problem began, I had shut down the
machine to examine its memory modules.  There are two memory slots;
one can be accessed through a panel on the underside of the machine,
while the other requires that the keyboard be removed to access it.
I confirmed that both slots contain 2GB DDR3 SODIMMs (I want to
upgrade it from 4GB to 8GB of memory).  It was after buttoning it up
and restarting it that the networking hardware vanished (unless I boot
from the Windows 7 partition).  If I had really broken the networking
hardware by poking around inside the machine, I would expect that
networking would be broken under Win7 as well.

I found an old backup of the hard drive; its /etc/network/interfaces
also contains only an entry for "lo", and /etc/network/interfaces.d
is empty.  Is this information stored somewhere else?

Is there a way I could activate the code that the Linux installer uses
to automatically detect networking hardware without doing a re-install?
Or are there other things I can try to track down the problem?

Many thanks for whatever assistance you can provide.

--
/~\  Charlie Gibbs                  |  Life is perverse.
\ /  <cgibbs@kltpzyxm.invalid>      |  It can be beautiful -
 X   I'm really at ac.dekanfrus     |  but it won't.
/ \  if you read it the right way.  |    -- Lily Tomlin