Hi everyone 
Please excuse me for this post, it’s definitely a newbie problem and a schoolkid error. I have used web search a lot to try and find an answer but nothing that I can easily follow. If this is the wrong place to ask this question then please point me to where I should ask.
I have made a mistake setting up a VM GPU passthrough on a work Ubuntu laptop, and now the laptop is unusable. I enabled GPU passthrough for the integrated Intel GPU for a Win11 VM (trying to get CAD working) and when I started the VM the screen went blank. I did this in the LXD UI, not the terminal. The GPU passthrough was physical. I tried lots of keyboard shortcuts to try and get the screen to come back, but it didn’t work, though I imagine there’s probably a quick way to recover from this issue. I have been able to turn the laptop off with the power button, both soft shutdown and hard stop, though soft shutdown takes a loooonnng time, takes ages to kill XOrg. The laptop will boot to the login screen, but then the screen goes blank. I believe this is because lxd starts and isolates the integrated GPU for the use of the VM, and Ubuntu on the laptop cannot use it, so can no longer display the desktop. The laptop does have a second discrete GPU, an NVidia one, which I would have done GPU passthrough with but at the time it was actually the one running XOrg according to the error message I got when I tried to start the VM with this config.
One thing I can do is get to the terminal through GRUB, but this is of course with nothing loaded. From here I installed openssh-server but when I let the laptop boot to login screen again it did not appear on my local network, so I don’t think I can even SSH in and fix things.
I imagine I need to somehow change the lxd config to remove the GPU passthrough, but so far I’ve not wrapped my head around how I can do that without starting lxd and therefore activating the passthrough and losing the screen again. Could you please advise how I can fix the problem? I will continue to try and find answers and attempt to fix this.
Cheers