The error ModuleNotFoundError: No module named '_ctypes' can occur when you try to run Jupyter Notebook and means that the _ctypes module, which is a part of the Python Standard Library, is not found. This can be caused by several factors, including a missing or corrupt Python installation, or a misconfigured environment.

Here are some steps that you can try to fix this error:

1. Make sure that you have Python and pip, the Python package manager, installed on your system. You can check if Python is installed by running the following command in a terminal:

python3 --version

If Python is not installed, you can install it by running the following command:

sudo apt-get install python3 python3-pip

2. Make sure that the _ctypes module is not missing from your Python installation. You can check if the _ctypes module is present by running the following command in a terminal:

python3 -c "import _ctypes"

If the module is missing, you may need to reinstall Python or restore the missing files from a backup.

3. Make sure that the correct version of Python is being used when you run Jupyter Notebook. If you have multiple versions of Python installed on your system, you may need to specify the path to the correct Python executable. For example:

/usr/bin/python3 -m jupyter notebook

4. If you are using a virtual environment or conda environment, make sure that it is activated and that the necessary packages are installed. You can activate a virtual environment by running the following command in a terminal:

source path/to/venv/bin/activate

And you can activate a conda environment by running the following command:

conda activate envname