Hello. Im running kde neon with plasma 5.12.3. I was running some programs and used sudo xkill on an open tab in the panel(i think it was for discover). As soon as i did this my screen went black with only mouse cursor visible. Doing hard reboot loads up a screen saying 'kde neon 5.12.3 'with a progress bar but eventually takes me back to a black screen with only mouse cursor visible. I get no greeter screen. I am a linux newb. Pls help

SOLVED !!!
i solved the problem. the issue was that i had recently used back-in-time to make a backup of my system and this caused my home folder to become full. This apparently doesnt allow the gui to load in startup. i went to the tty2 and deleted the snapshot , deleted /tmp and then remade tmp. restarting cleared up the problem. i have been looking for a solution for past 24hrs. i thought it was something to do with sddm or Xserver. Its very frustrating but thank God i was able to stumble upon the solution.