Sounds like gpu died, or drivers did. If you have another laptop or anything to ssh from, see if you can get into the box via ssh and troubleshoot that way. I've popped video cards to die before, and they work, but only headless.
Try to 'cat /var/log/Xorg.0.log' to see if your card died, or updated perhaps unexpectedly. Sadly updating some minor 3rd party crap would occasionally break my whole update and os, ubuntu or arch really. Last time I upgraded my arch it broke nvidia binary support with too new a kernel, luckily I never use the nvidia gpu as prime is a basketcase anyways, so it uses intel normally anyways. Above old laptop example worked if I disable nvidia drivers and used only intel, as the gpu fried. Yours might have if video is just dead, but otherwise seems alive.
If only intel, your software may have just gotten hozed - try a different user profile if you can get any video out of it.
-mb