> Was X working before you tried the nvidia driver? Does /etc/xorg.conf
> exist now? If so, rename it so you can revert to a working X.
>
> Maybe try 'apt-get -f install' (without any packages named) to install any
> missing dependencies. I don't think that will do it, but it's worth a try.
>
> Someone else is having similar problems, and it seems there's a mismatch
> in versions of the different parts of nvidia.
> https://dev1galaxy.org/viewtopic.php?id=1540
>
> I've used the nvidia driver in the past, and I tended to have better luck
> using the binaries downloaded from nvidia. There are some tricks with
> that, too. (you have to use the version of gcc that was used to compile
> the kernel, and in debian stable, that's always an older version than the
> default.) If you decide to go that route, make sure you remove all nvidia
> packages from your system first.
Not to be rude, but I wouldn't trust nvidia drivers even if they were
completely sandboxed.

They A: hate free software, B: they require proprietary firmware and C:
Are a huge security risk,

then again, most processors are too... but that's besides the point.