I had a case of plasmashell turning into a zombi. This is what I did to solve it:
The correct way to restart plasmashell is trough: "plasmashell --replace &"
However, the old plasmashell was a zombi for some reason so I had to first kill it with:
523 sudo killall plasmashell
524 sudo kill {pid of the proces}
525 ps aux | grep plasmashell
526 cat /proc/{pid of the process}/status
527 sudo kill {pid}
531 ps o ppid {pid}
533 ps aux | grep -w Z #shows zombi processes
535 ps o ppid {pid}
536 sudo kill -1 {pid}
539 grep plasma*
# 540 killall plasmashell && kstart5 plasmashell& #this seems to be the old way to do it
Then Alt+F2 and
plasmashell --replace &
Also see this link.
