all the computers, except for two, were working. I
have those two and this one isn't one of them so I
know it must have been working. Closing the task.

Last night this computer had the same problem - no
display.  I adjusted the graphics connector and it
worked.  I could not get it to work tonight.

The graphics cable has an extra adapter and
appears there's been too much force (from butting
into the computer behind it) which bent the
adapter connection.