I’ve seen this happen several times now on Ubuntu-Linux based systems that have NVIDIA graphics.  What happens is that “Update Manager” pops up and tell you there are updates for your software, and you accept them.  It then tells you that your system has to be rebooted.  And when you do that, you get no video, or text only.  What probably happened was that the updates you installed included an update to the Linux kernel, and the NVIDIA graphics driver currently installed on the system was compiled against the OLD kernel.

Note that this generally can only happen if you manually updated the NVIDIA graphics driver at some point. If you always installed it from the standard repositories for your distribution, you’ll probably never see this issue. So a word to the wise — when you finally get around to doing an upgrade of your Linux distribution, try to avoid manually installing the NVIDIA graphics driver. Instead, let the distribution pull it from its repository. After that, you should not have this issue in the future. By the way, if you currently are running Ubuntu, we recommend upgrading to Linux Mint rather than a newer version of Ubuntu. Linux Mint is very similar to Ubuntu, but leaves out some of the things that users seem to hate about newer releases of Ubuntu. More to the point, they are not currently talking about switching their base graphics system from the X window server system to a new display manager, which I have a feeling might cause problems for some NVIDIA graphics users.

But if you’re not yet ready to do a full reinstall of Linux, the fix for this problem is easy IF you had the foresight to set up SSH access to your Linux system BEFORE the trouble started.  If you didn’t, and you’re not a true Linux geek, you may be kind of screwed.  So if you’re reading this and your system is working fine, and you haven’t yet set up SSH access, you may want to do that.  There are several sites that tell you how to do that; here are two that I found using Google:

Basic SSH Setup On Ubuntu 10.04 Lucid Lynx Using OpenSSH Server
SSH—OpenSSH—Configuring

If you didn’t do this beforehand, you may still be able to do it if you can get to a command prompt.

Anyway, the actual fix is to (re-)install the latest NVIDIA driver for your system. They will be compiled against the new Linux kernel and then everything should work fine. To find the correct NVIDIA driver, go to the NVIDIA Driver Downloads page, and use the dropdowns to select the correct driver for your system.  Download it to your local system, then upload it to your Linux PC (if you have SSH access working then you can use an SFTP client, such as WinSCP or Transmit, to upload your driver file).  Once you have it on your PC, from a command prompt navigate to the directory where you put the driver and then change the permissions to make it executable:

sudo chmod +x driver_upgrade_script_filename

Now try running the script (it should have a .run extension):

sudo ./driver_upgrade_script_filename

It should not complain that the Gnome Display Manager or KDE Display Manager is running (if it were, you wouldn’t be in a state of near-panic right now), but if you were just doing a regular update you’d have to do this when the GDM/KDM is stopped. For a guide that covers that scenario, see How To Install Official Nvidia Drivers in Linux, or just know that to stop the display manager,

sudo /etc/init.d/gdm stop

should stop the Gnome Display Manager, or if you’re using KDE then the command would be

sudo /etc/init.d/kdm stop

Most sources I’ve seen suggest that you answer yes to any questions the installer may ask. The only one I’d be cautious about is letting it create a new xorg.conf if you are using a customized one (which you may well be if you’ve used any of my previous HTPC-related articles). If you have edited xorg.conf, then I’d make sure you at least have a backup before letting the installer create a new one, so you can revert back to your custom one (or compare the two and insert your customizations into the new one) if necessary.

Under Ubuntu, you may get a message similar to “Provided install script failed”. That will happen every time you update the NVIDIA driver this way and it is normal. Just ignore it and continue the installation. If you get “Error locating kernel source”, run  sudo apt-get install kernel-source  from the command prompt, then run the driver upgrade script again.

When the installer has successfully finished, reboot the system and when it comes back up, hopefully you should be happy again!