Error message for command nvcc --version and nvidia-smi

Accelerated Computing CUDA CUDA Setup and Installation
1

I was trying to donwload CUDA version 11.8 on Ubuntu and I was following CUDA Toolkit 11.8 Downloads | NVIDIA Developer. The CUDA used to be version 11.5 on my computer. I did not check the pre-dowload and I have checked after and realized that my GPU is not CUDA capable.

  1. Now when I run nvcc --version, I got an error message saying Command ‘nvcc’ not found, but can be installed with:
    sudo apt install nvidia-cuda-toolkit and I tried to download the toolkit, I got Reading package lists… Done
    Building dependency tree… Done
    Reading state information… Done
    Some packages could not be installed. This may mean that you have
    requested an impossible situation or if you are using the unstable
    distribution that some required packages have not yet been created
    or been moved out of Incoming.
    The following information may help resolve the situation:

The following packages have unmet dependencies:
libcuinj64-11.5 : Depends: libnvidia-compute-495 (>= 495) but it is not going to be installed or
libnvidia-compute-495-server (>= 495) but it is not installable or
libcuda.so.1 (>= 495) or
libcuda-11.5-1
libnvidia-ml-dev : Depends: libnvidia-compute-495 (>= 495) but it is not going to be installed or
libnvidia-compute-495-server (>= 495) but it is not installable or
libnvidia-ml.so.1 (>= 495)
nvidia-cuda-dev : Depends: libnvidia-compute-495 (>= 495) but it is not going to be installed or
libnvidia-compute-495-server (>= 495) but it is not installable or
libcuda.so.1 (>= 495) or
libcuda-11.5-1
Recommends: libnvcuvid1 but it is not installable

  1. And I was trying to run command nvidia-smi. I got an error message saying NVIDIA-SMI has failed because it couldn’t communicate with the NVIDIA driver. Make sure that the latest NVIDIA driver is installed and running.

I am wondering how to solve these two issues? I want to revert back the installation and get to work with my old version. But my cuda-11.5 link is shown as broken. Also, now my screen turned blue like having a blue layer on top. I am not sure if this is also caused by installing the 11.8 version.