Having tried to install the proprietary Nvidia drivers several times and always ending up with a black screen and various difficulties trying to return the X server and Unity to a functional state, I was somewhat surprised when I clicked on the nvidia-352 radio button in the Proprietary Drivers (or whatever it is called now) tab in the Repositories window in Synaptic Package Manager, and rebooted right into a functional Nvidia session.

I’ve been struggling with this ever since I upgraded to 15.10. Everything I’ve read amounted to basically the same fix: purge any leftover Nvidia drivers, reinstall and reconfigure X. There’s been no mention of this, anywhere. Can somebody please explain to me what happened?