Deleted old .xauth cookies; now Plasma won't start

[FlyingWafflez]

So I was messing around and deleting old files from my root and user home directories, when like an idiot, I deleted all the .xauth<hash> files in /root.
Now after rebooting and trying to log in again I cannot start Plasma from SDDM. SDDM runs fine, but trying to start Plasma, X, or Wayland sessions from there either does nothing or resets back to SDDM.

I managed to log into my user account on TTY4 and ran startx. This got me into a usable(ish) Plasma desktop but switching through TTYs and trying the same thing is giving me very mixed results (no-where else has successfully started a desktop session). And going back to TTY1 and trying to log in through SDDM still doesn't work. I've tried restarting SDDM, still no luck.

Strangely, where before I had multiple .xauth<hash> files in /root (the <hash> was literally some random 6 char string) after this messing around I now have .Xauthority files in both /root and /home/<user>. These were also absent until about 10 minutes after I got my desktop in TTY4 running. Before then 'xauth list' had returned nothing or timed out, it now returns two magic cookies.

Any help would be appreciated.


EDIT: After another reboot I have been able to login to the Plasma session through SDDM. I am still having issues with Wayland and XSession, both drop me back to SDDM after a few seconds. Also, logging out from Plasma and trying to log back in results in graphical breakage, with a frozen SDDM showing, but some of my keybinds such as Yakuake half working (still broken enough that I had to hard reboot).