Well for one thing... I am not sure how the NVIDIA drivers installed if they were the wrong version. It shouldn't install at all if it's the wrong version, at least that's how it has been in my experience.
What you could do is just hit up the command prompt. If you boot up and nothing is on the screen, hitting CTRL+ALT+F1 or CTRL+ALT+F2 should bring you to a login screen. Then once in, you could edit your xorg.conf.
vim /etc/X11/xorg.conf
Then you would need to scroll down to find the Driver "nvidia" and change "nvidia" to "vesa". Then after rebooting, things should be fine. To edit in vi, you need to hit your 'I' key, make the edits and then hit ESC. You can then save the file by typing ':w', without quotes.