On Lubuntu 19.04. Everything was going fine until recently when I simply started having a “black screen” (Xserver started, but perhaps not the display manager) with the mouse-pointer visible. Searching around I found many references to such issues for past versions of Ubuntu and Lubuntu, but nothing for 19.04. Frustrated and unable to fine any clear clues from logs (syslog, dmesg, Xorg logs), I attempted to reinstall xorg using dpkg using --reinstall (forced) command. That seemed to fail with no space left on device error. That gave me the hint, and I found that my /var was full. Removed all large log files and made sufficient space. However, after doing that I realized that now I do not get into the graphical desktop anymore, but I am left stranded at the shell login. On manually doing startx, I see that the desktop look-n-feel has changed (perhaps reverted to default theme), and I no longer see the network manager applet etc.
Unfortunately, I do not remember doing anything particularly different that might have led to the above situation, except for accepting a Firefox auto update.
What do I have to do to get the ability to directly land into the graphical desktop login page, and get back my old preferences/settings for the graphical desktop ?