How to kill and restart kwin and plasma-desktop from remote ssh session

I have a VNC machine running kde4 as the desktop environment, I logged into the VNC machine and the desktop was just displaying a black screen. To remedy this I ssh'd into the VNC host and ran pkill -ABRT kwin This made the graphical environment reappear, although some elements such as the task bar at the bottom and the window decorations which have icons for closing / minimising the windows are missing. The more pertinent issue however is that, while mouse inputs work, I cannot use my keyboard in any window that I open, and keyboard shortcuts are not registering either. I think that if I was able to, restarting the machine would solve my issue, however this option is not available to me, i.e. I have to fix this as a non-root user from an ssh session. However when I try to start plasma-desktop from the ssh session I get the following feedback:

connect /tmp/.X11-unix/X0: No such file or directory plasma-desktop(xxxxx): 
KUniqueApplication: Cannot find the D-Bus session server:  "/usr/bin/dbus-launch terminated abnormally with the following error: Autolaunch error: X11 initialization failed."

plasma-desktop(xxxxx): KUniqueApplication: Pipe closed unexpectedly.

Any help or suggestions anyone can provide would be much appreciated.