I just upgraded my Ubuntu from 14.10 to 15.10 (wily), but Ubuntu just display a black screen and can't display the login screen. I suspect it's an Nvidia driver issue, so I switched to tty1, and found there are some errors in the /var/log/Xorg.0.log file.
I already have Nvidia driver PPA installed (both for wily and utopic), and I also tried to upgrade the Nvidia driver by these commands：
sudo apt-get update
sudo apt-get install nvidia-340
but it told me "nvidia-340 is already the newest version". It that the problem which cause black screen? And how should I do it? btw, my Nvidia graphicscard is Quadro K620. Below are some fragments of Xorg.0.log:
[ 13.491] (II) Module glx: vendor="NVIDIA Corporation" [ 13.491] compiled for 4.0.2, module version = 1.0.0 [ 13.491] Module class: X.Org Server Extension [ 13.491] (II) NVIDIA GLX Module 340.76 Thu Jan 22 11:24:42 PST 2015 ..... [ 13.491] (EE) Failed to load module "nouveau" (module does not exist, 0) ..... [ 13.491] (EE) Failed to load module "fbdev" (module does not exist, 0) ..... [ 13.491] (EE) Failed to load module "vesa" (module does not exist, 0) ..... [ 13.492] (EE) Failed to load module "nouveau" (module does not exist, 0) ..... [ 13.492] (EE) Failed to load module "fbdev" (module does not exist, 0) ..... [ 13.492] (EE) Failed to load module "vesa" (module does not exist, 0) [ 13.492] (II) NVIDIA dlloader X Driver 340.76 Thu Jan 22 11:03:05 PST 2015 [ 13.492] (II) NVIDIA Unified Driver for all Supported NVIDIA GPUs [ 13.492] (II) modesetting: Driver for Modesetting Kernel Drivers: kms ..... [ 13.494] (EE) NVIDIA: Failed to initialize the NVIDIA kernel module. Please see the [ 13.494] (EE) NVIDIA: system's kernel log for additional error messages and [ 13.494] (EE) NVIDIA: consult the NVIDIA README for details. [ 13.494] (EE) open /dev/dri/card0: No such file or directory [ 13.494] (EE) open /dev/dri/card0: No such file or directory [ 13.494] (WW) Falling back to old probe method for modesetting [ 13.494] (EE) open /dev/dri/card0: No such file or directory [ 13.494] (EE) open /dev/dri/card0: No such file or directory [ 13.494] (EE) Screen 0 deleted because of no matching config section. [ 13.494] (II) UnloadModule: "modesetting" [ 13.494] (EE) Screen 0 deleted because of no matching config section. [ 13.494] (II) UnloadModule: "modesetting" [ 13.494] (EE) Device(s) detected, but none match those in the config file. [ 13.494] (EE) Fatal server error: [ 13.494] (EE) no screens found(EE) [ 13.494] (EE) Please consult the The X.Org Foundation support at http://wiki.x.org for help. [ 13.494] (EE) Please also check the log file at "/var/log/Xorg.0.log" for additional information. [ 13.494] (EE) [ 13.643] (EE) Server terminated with error (1). Closing log file.
