I'm having a problem with booting into Ubuntu 14.04 through my GTX 970 graphics card. I had installed it previously onto my system along with the NVIDIA driver and it was working fine for the most part despite some hiccups but I recently tried to update some drivers but it didn't update correctly. I can't boot correctly anymore; all I get is either a black screen or a a screen with a text blinker on it (the proper name for it escapes me at the moment). I can get to the GRUB menu sometimes and have tried to update but get the errors shown here: errors. Entering through recovery mode can get me to the login screen but trying to login just brings me back to the login screen! I don't have much experience in fixing Ubuntu in this way so please help if you can. I have tried other solutions but they haven't seemed to work for me.
I had the same problem for a while with my GTX 970 and I fixed it by using the boot-repair.
First you need to somehow get the ubuntu to boot in recovery mode. If that doesn't work try logging into the shell by pressing Ctrl+Alt+F3
Once you log in, then you should run boot repair: https://help.ubuntu.com/community/Boot-Repair
For some reason, everytime I use the GTX 970 driver to run my monitors, I had to do boot-repair...
I had virtually the same problem on the same system: Ubuntu 14.04 with GTX 970.
I had installed the NVIDIA drivers from the website. What worked for me in the end was:
Go to recovery mode (graphics fail safe mode)
Enter Terminal (Ctrl+ALT+F1)
sudo stop lightdm(or was it:
sudo service lightdm stop)
Run the original installer file
sudo NVIDIA.your version here.run --update
Note: it seems like a flaky and bothersome solution considering this appears to be a common problem. However, just uninstalling the driver with the script didn't fix my problem (maybe I forgot to stop lightdm beforehand?). If it works for you, I suggest uninstalling and switching to the open drivers by installing
sudo apt-get install nvidia-current-updates nvidia-settings-updates
(not sure where I saw that)