This could be the result of a few problems. First of all, this implies that your python language server does not have the packages installed. You said that when you reinstalled the packages it said they are already installed, therefore I assume your code looks for the wrong python version.

If you used a virtual environment (like venv for example) to setup your installed packages, then you probably need to activate it (run the activate script in the terminal you want to run your python code. On Windows its a .bat file, on Linux you can do source .../activate)

If you did not use a virtual environement, there can be multiple versions of python installed. Figure out which one you use when you install the packages and try to run your program with this version directly. Also, if your code is from a jupyter notebook, see if you selected the right python kernel.

Finally, you didn't say whether you tried running the problem. Did you get an error? If the program works just fine, then only the language server has a problem and it might be an issue with the IDE.

I hope this helps.