After removing the proprietary driver, the system does not start, how to start?

Question

Debian

On startup, first this:

And then a flashing underscore, the nouveau driver is installed

I tried to start nouveau for a long time but changed my mind

Solution:
You can burn a new version of debian live to a USB flash drive and see how the new nouveau works on your video card
https://www.debian.org/ distrib
If bad just boot into recovery mode and install the nvidia drivers back

Here are the new repositories (if the system is debian 11)
nano /etc/apt/sources.list
deb deb.debian.org/debian bullseye main
deb deb.debian.org/debian bullseye non-free
deb deb.debian.org/debian bullseye contrib
apt update

Stupid mistake:
check if you made a mistake and did not write byllseye instead of bullseye for example, I therefore could not install the nvidia drivers back

Then everything is as usual:
apt install nvidia-detect
nvidia-detect
it will show which driver you need
apt install your driver which you need showed nvidia detect the same recommended
apt install nvidia-xconfig
nvidia-xconfig
apt remove nvidia-detect
apt remove nvidia-xconfig

Answer 1

single or emergency when booting into kernel parameters, single user mode, replacing all occurrences of nvidia with nouevau, or removing all mentions of nvidia (including in kernel parameters, if it is present there)