I ran dpkg --get-selections to get all my installed packages and here's the installed Nvidia stuff. Try to install what's missing.
If you can't even get to command line, try to backup your data to an external source by using a live USB, and replace your debian with Pika OS, which has all the Nvidia stuff out the gate.
nvidia-alternative
nvidia-driver
nvidia-driver-bin
nvidia-driver-libs:amd64
nvidia-driver-libs:i386
nvidia-egl-common
nvidia-egl-icd:amd64
nvidia-egl-icd:i386
nvidia-installer-cleanup
nvidia-kernel-common
nvidia-kernel-dkms
nvidia-kernel-support
nvidia-legacy-check
nvidia-modprobe
nvidia-persistenced
nvidia-settings
nvidia-smi
nvidia-support
nvidia-suspend-common
nvidia-vdpau-driver:amd64
nvidia-vulkan-common
nvidia-vulkan-icd:amd64
nvidia-vulkan-icd:i386
EDIT : from apt list --installed
libnvidia-allocator1/stable,now 550.163.01-2 amd64 [installed,automatic]
libnvidia-allocator1/stable,now 550.163.01-2 i386 [installed,automatic]
libnvidia-cfg1/stable,now 550.163.01-2 amd64 [installed,automatic]
libnvidia-egl-gbm1/stable,now 1.1.2.1-1 amd64 [installed,automatic]
libnvidia-egl-gbm1/stable,now 1.1.2.1-1 i386 [installed,automatic]
libnvidia-egl-wayland1/stable,stable,now 1:1.1.18-1 amd64 [installed,automatic]
libnvidia-egl-wayland1/stable,stable,now 1:1.1.18-1 i386 [installed,automatic]
libnvidia-eglcore/stable,now 550.163.01-2 amd64 [installed,automatic]
libnvidia-eglcore/stable,now 550.163.01-2 i386 [installed,automatic]
libnvidia-encode1/stable,now 550.163.01-2 amd64 [installed,automatic]
libnvidia-encode1/stable,now 550.163.01-2 i386 [installed,automatic]
libnvidia-glcore/stable,now 550.163.01-2 amd64 [installed,automatic]
libnvidia-glcore/stable,now 550.163.01-2 i386 [installed,automatic]
libnvidia-glvkspirv/stable,now 550.163.01-2 amd64 [installed,automatic]
libnvidia-glvkspirv/stable,now 550.163.01-2 i386 [installed,automatic]
libnvidia-gpucomp/stable,now 550.163.01-2 amd64 [installed,automatic]
libnvidia-gpucomp/stable,now 550.163.01-2 i386 [installed,automatic]
libnvidia-ml1/stable,now 550.163.01-2 amd64 [installed,automatic]
libnvidia-pkcs11-openssl3/stable,now 550.163.01-2 amd64 [installed,automatic]
libnvidia-ptxjitcompiler1/stable,now 550.163.01-2 amd64 [installed,automatic]
libnvidia-ptxjitcompiler1/stable,now 550.163.01-2 i386 [installed,automatic]
libnvidia-rtcore/stable,now 550.163.01-2 amd64 [installed,automatic]