[PLUG] Cannot get to printer

[Denis Heidtmann]

I had no problem until yesterday.  It has likely been a number days since I
last used it, and maybe a system update was performed in the interim, but
nothing major.

In the GUI System Settings, Printers I try -localhost -connect I get a
window "cups server error: There was an error during the cups  operation:
'failed to connect to server'.  Next I tried:

sudo systemctl restart cups.service.  Msg is:
"failed to restart cups.service: unit cups.service is masked"

Next I tried:
sudo systemctl stop cups.service: no messages in response.

A repeat of:
sudo systemctl restart cups.service.  Msg is the same:
"failed to restart cups.service: unit cups.service is masked"

Next effort:
systemctl list-unit-files generates a 16kbyte list of 310 unit files.
There are 4 cups entries; all showing a state of masked:
cups.path, cups.service, cups-browsed.service, and cups.socket

A table in the docs indicates that masked means "Completly disabled, so
that any start operation on fails (permanently in /etc/systemd/system/ or
transiently in /run/systemd/systemd/"

/etc/systemd/system/ has the 4 files listed above, all of zero length.
/run/systemd/systemd/" does not exist. (doc. misprint?)
/run/systemd/system/" exists but has nothing that means anything to me.

Does all this info help anyone with suggestions?  Running Ubuntu 16.04.

Thanks,
-Denis