i'm running ubuntu 15.04, nvidia card 970gtx, drivers installed manually using nvidias script. i have fake raid 0 to dual boot windows 7 and ubuntu. i also have 4 drives using mdadm for raid 5. everything was wonderful until..
one day i was fiddling around with the powerstrip my computer is connected to when i accidentally flicked it off. the computer was running at the time. so i turned it back on and all i got was the grub prompt...
from there i tried a bunch of stuff to fix up grub to get back the option to boot ubuntu but nothing worked. so i made a live usb and booted that (efi mode). i could without issue mount the windows partition but the ubuntu partition was borked. so i cracked open gparted. it said something was wrong with my ubuntu partition so i right clicked it and told it to repair it (cant remember what the right click menu said). after that, i could mount the partition. so i happily restarted.
it tried to boot ubuntu, woohoo! but every time it says, "low graphics mode" blah blah. so i switched over to run level 3. fine i said, ive seen this a million times before, ill just reinstall the nvidia drivers and be on my way. killed the procs showing the low graphics warning. installed tthe nvidia drivers. restarted, same thing. tried many times.
again in run level 3 after some googling i found that i can mess with lightdm using systemd. so i issue
systemctl restart lightdm.service and what do you know graphical login comes up and it all works.
and that is where i am, i have to manually start lightdm with systemctl. i tried
dpkg-reconfigure xserver-xorg i tried puring lightdm and reinstalling it. its always the same outcome with low graphics mode.
currently i am looking at the output of
systemctl status lightdm.service:
● lightdm.service - Light Display Manager Loaded: loaded (/lib/systemd/system/lightdm.service; enabled; vendor preset: enabled) Drop-In: /lib/systemd/system/display-manager.service.d └─xdiagnose.conf Active: failed (Result: start-limit) since Sat 2016-01-16 13:39:54 EST; 32s ago Docs: man:lightdm(1) Process: 1573 ExecStart=/usr/sbin/lightdm (code=exited, status=1/FAILURE) Process: 1569 ExecStartPre=/bin/sh -c [ "$(basename $(cat /etc/X11/default-display-manager 2>/dev/null))" = "lightdm" ] (code=exited, status=0/SUCCESS) Main PID: 1573 (code=exited, status=1/FAILURE) Jan 16 13:39:54 GA-H97N-WIFI systemd: lightdm.service failed. Jan 16 13:39:54 GA-H97N-WIFI systemd: lightdm.service holdoff time over, scheduling restart. Jan 16 13:39:54 GA-H97N-WIFI systemd: start request repeated too quickly for lightdm.service Jan 16 13:39:54 GA-H97N-WIFI systemd: Failed to start Light Display Manager. Jan 16 13:39:54 GA-H97N-WIFI systemd: Unit lightdm.service entered failed state. Jan 16 13:39:54 GA-H97N-WIFI systemd: Triggering OnFailure= dependencies of lightdm.service. Jan 16 13:39:54 GA-H97N-WIFI systemd: lightdm.service failed.
i saw another answer that said something was wrong with
/var/lib/lightdm but mine is there and intact.. so not sure..