I have a very old Nvidia card (8800GTX), using yum to attempt to install video drivers proves to make my system not boot. Fun.
Download your drivers from here
To install you can’t be running X windows so you will need to log-out and drop to run level 3 or just reboot the system into run level 3.
Using Fedora 21, boot system to grub2, hit ‘e’ (edit).. find the linux line and hit your ‘end’ key to goto the end of the linux and type ‘3’ (for run level 3)
then either hit F10 or cntl-x… if all goes correct then you will be looking at login prompt without the gui.
Enter in your user/pass, change directory to the place that you downloaded the driver.. ~/Downloads. You may need to set the permissions .
sudo chmod +x NVIDIA-Linux-x86_64-340.76.run or chmod 755 NVIDIA-Linux-x86_64-340.76.run
Let that run, and once that is done, you can reboot.
Hopefully that goes smoothly and you should be looking at the gui login prompt, if not, then boot the system into run level 3 again and start troubleshooting. Hopefully you have another system you can use to help troubleshoot or I’d just un-install the nvidia driver.