This situation occurred to me when I uninstalled a method and tried to reinstall it. My very same interpreter, which worked before, suddenly stopped working. And this error occurred.
I tried restarting my PC, reinstalling Pycharm, invalidating caches, nothing worked.
Then I went here to reinstall the interpreter: https://www.python.org/downloads/
When you install it, there's an option to fix the python.exe interpreter. Click that. My IDE went back to normal working conditions.